Method and apparatus for controlling ue transmission power in wireless communication system

ABSTRACT

The disclosure relates to a communication method and a system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. §119(a) of a Korean patent application number 10-2019-0016921, filed onFeb. 13, 2019, in the Korean Intellectual Property Office, of a Koreanpatent application number 10-2019-0035894, filed on Mar. 28, 2019, inthe Korean Intellectual Property Office, and of a Korean patentapplication number 10-2019-0068209, filed on Jun. 10, 2019, in theKorean Intellectual Property Office, the disclosure of each of which isincorporated by reference herein in its entirety.

BACKGROUND 1. Field

The disclosure relates to a method for controlling user equipment (UE)transmission power in a wireless communication system. Moreparticularly, the disclosure relates to a method and an apparatus forsetting transmission power when a UE (terminal) transmits a sidelinkcontrol channel and a sidelink data channel.

2. Description of Related Art

To meet the demand for wireless data traffic having increased sincedeployment of 4th generation (4G) communication systems, efforts havebeen made to develop an improved 5^(th) generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post long term evolution(LTE) System’. The 5G communication system is considered to beimplemented in higher frequency (millimeter (mm) Wave) bands, e.g., 60gigahertz (GHz) bands, so as to accomplish higher data rates. Todecrease propagation loss of the radio waves and increase thetransmission distance, the beamforming, massive multiple-inputmultiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna,an analog beam forming, large scale antenna techniques are discussed in5G communication systems. In addition, in 5G communication systems,development for system network improvement is under way based onadvanced small cells, cloud Radio Access Networks (RANs), ultra-densenetworks, device-to-device (D2D) communication, wireless backhaul,moving network, cooperative communication, Coordinated Multi-Points(CoMP), reception-end interference cancellation and the like. In the 5Gsystem, Hybrid Frequency-shift keying (FSK) and Quadrature AmplitudeModulation (QAM) (FQAM) and sliding window superposition coding (SWSC)as an advanced coding modulation (ACM), and filter bank multi carrier(FBMC), non-orthogonal multiple access (NOMA), and sparse code multipleaccess (SCMA) as an advanced access technology have been developed.

The Internet, which is a human centered connectivity network wherehumans generate and consume information, is now evolving to the Internetof Things (IoT) where distributed entities, such as things, exchange andprocess information without human intervention. The Internet ofEverything (IoE), which is a combination of the IoT technology and theBig Data processing technology through connection with a cloud server,has emerged. As technology elements, such as “sensing technology”,“wired/wireless communication and network infrastructure”, “serviceinterface technology”, and “Security technology” have been demanded forIoT implementation, a sensor network, a Machine-to-Machine (M2M)communication, Machine Type Communication (MTC), and so forth have beenrecently researched. Such an IoT environment may provide intelligentInternet technology services that create a new value to human life bycollecting and analyzing data generated among connected things. IoT maybe applied to a variety of fields including smart home, smart building,smart city, smart car or connected cars, smart grid, health care, smartappliances and advanced medical services through convergence andcombination between existing Information Technology (IT) and variousindustrial applications.

In line with this, various attempts have been made to apply 5Gcommunication systems to IoT networks. For example, technologies such asa sensor network, Machine Type Communication (MTC), andMachine-to-Machine (M2M) communication may be implemented bybeamforming, MIMO, and array antennas. Application of a cloud RadioAccess Network (RAN) as the above-described Big Data processingtechnology may also be considered to be as an example of convergencebetween the 5G technology and the IoT technology.

In accordance with what described above and the development of a mobilecommunication system, various services can be provided, and a plan toeffectively provide these services is thus required.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea method for controlling transmission powers of a sidelink controlchannel and a sidelink data channel.

In an aspect of the disclosure, a method performed by a first userequipment (UE) in a wireless communication system is provided. Themethod includes receiving, from a base station, a radio resource control(RRC) message including information related to sidelink transmissionpower, determining sidelink transmission power, based on theinformation, and transmitting a sidelink control channel and a sidelinkdata channel, based on the determined sidelink transmission power,wherein the information includes at least one of downlink pathloss-related information or sidelink path loss-related information.

In another aspect of the disclosure, a method performed by a basestation in a wireless communication system is provided. The methodincludes transmitting, to a first UE, an RRC message includinginformation related to sidelink transmission power, and receiving, fromthe first UE, a sidelink control channel and a sidelink data channel,based on sidelink transmission power, wherein the sidelink transmissionpower is determined based on the information, and wherein theinformation includes at least one of downlink path loss-relatedinformation or sidelink path loss-related information.

In another aspect of the disclosure, a first UE is provided. The firstUE includes a transceiver configured to transmit or receive at least onesignal, and at least one processor coupled to the transceiver. The atleast one processor is configured to receive, from a base station, anRRC message including information related to sidelink transmissionpower, determine sidelink transmission power, based on the information,and transmit a sidelink control channel and a sidelink data channel,based on the determined sidelink transmission power, and wherein theinformation includes at least one of downlink path loss-relatedinformation or sidelink path loss-related information.

In another aspect of the disclosure, a base station is provided. Thebase station includes a transceiver configured to transmit or receive atleast one signal, and at least one processor coupled to the transceiver.The at least one processor is configured to transmit, to a first UE, anRRC message including information related to sidelink transmissionpower, and receive, from the first UE, a sidelink control channel and asidelink data channel, based on sidelink transmission power, wherein thesidelink transmission power is determined based on the information, andwherein the information includes at least one of downlink pathloss-related information or sidelink path loss-related information.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to the technology, transmission powers of a sidelink controlchannel and a sidelink data channel can be effectively controlled.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A illustrates a system according to an embodiment of thedisclosure;

FIG. 1B illustrates a system according to an embodiment of thedisclosure;

FIG. 1C illustrates a system according to an embodiment of thedisclosure;

FIG. 1D illustrates a system according to an embodiment of thedisclosure;

FIG. 2A illustrates a vehicle to everything (V2X) communication methodperformed via sidelink according to an embodiment of the disclosure;

FIG. 2B illustrates a V2X communication method performed via sidelinkaccording to an embodiment of the disclosure;

FIG. 3 illustrates V2X transmission power control according to anembodiment of the disclosure;

FIG. 4 illustrates interference caused by a frequency block transmittedby a V2X UE in an adjacent frequency block according to an embodiment ofthe disclosure;

FIG. 5 illustrates interference caused by a frequency block transmittedby a V2X UE in an adjacent frequency block according to an embodiment ofthe disclosure;

FIG. 6 illustrates V2X transmission power control according to anembodiment of the disclosure;

FIG. 7 is a diagram illustrating a sidelink resource for performing V2Xcommunication according to an embodiment of the disclosure;

FIG. 8 illustrates a multiplexing method of a sidelink control channeland a sidelink data channel within a sidelink resource according to anembodiment of the disclosure;

FIG. 9 illustrates a multiplexing method of a sidelink control channeland a sidelink data channel within a sidelink resource according to anembodiment of the disclosure;

FIG. 10 illustrates a multiplexing method of a sidelink control channeland a sidelink data channel within a sidelink resource according to anembodiment of the disclosure;

FIG. 11 illustrates a multiplexing method of a sidelink control channeland a sidelink data channel within a sidelink resource according to anembodiment of the disclosure;

FIG. 12 illustrates a multiplexing method of a sidelink control channeland a sidelink data channel within a sidelink resource according to anembodiment of the disclosure;

FIG. 13 illustrates a multiplexing method of a sidelink channel within asidelink resource according to an embodiment of the disclosure;

FIG. 14 illustrates an operational flowchart of a V2X UE for sidelinktransmission power control according to an embodiment of the disclosure;

FIG. 15 is a diagram illustrating a UE configuration according to anembodiment of the disclosure; and

FIG. 16 is a diagram illustrating a base station's configurationaccording to an embodiment of the disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thedisclosure. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of thedisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of thedisclosure is provided for illustration purpose only and not for thepurpose of limiting the disclosure as defined by the appended claims andtheir equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

In describing the embodiments, descriptions of technologies which arealready known in the technical field to which the disclosure belongs andare not directly related to the disclosure are omitted. Such an omissionof unnecessary descriptions is intended to prevent obscuring of the mainidea of the disclosure and more clearly transfer the main idea.

For the same reason, in the accompanying drawings, some elements areexaggerated, omitted, or schematically illustrated. Further, the size ofeach element does not entirely reflect the actual size. In the drawings,identical or corresponding elements are provided with identicalreference numerals.

The advantages and features of the disclosure and ways to achieve themwill be apparent by making reference to embodiments as described belowin detail in conjunction with the accompanying drawings. However, thedisclosure is not limited to the following embodiments and may beimplemented in various different forms, and the embodiments of thedisclosure are provided to make the disclosure perfect and completelyinform those skilled in the art of the scope of the disclosure and thedisclosure is only defined by the scope of the claims. Throughout thespecification, the same or like reference numerals designate the same orlike elements.

Here, it will be understood that each block of the flowchartillustrations, and combinations of blocks in the flowchartillustrations, can be implemented by computer program instructions.These computer program instructions can be provided to a processor of ageneral purpose computer, special purpose computer, or otherprogrammable data processing apparatus, such that the instructions,which execute via the processor of the computer or other programmabledata processing apparatus, create means for implementing the functionsspecified in the flowchart block or blocks. These computer programinstructions may also be stored in a computer usable orcomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer usable orcomputer-readable memory produce an article of manufacture includinginstruction means that implement the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operations to be performed on the computer or otherprogrammable data processing apparatus to produce a computer implementedprocess such that the instructions that execute on the computer or otherprogrammable data processing apparatus provide operations forimplementing the functions specified in the flowchart block or blocks.

In addition, each block of the flowchart illustrations may represent amodule, segment, or portion of code, which includes one or moreexecutable instructions for implementing the specified logicalfunction(s). It should also be noted that in some alternativeimplementations, the functions noted in the blocks may occur out of theorder. For example, two blocks shown in succession may in fact beexecuted substantially concurrently or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved.

As used herein, the “unit” refers to a software element or a hardwareelement, such as a field programmable gate array (FPGA) or anapplication specific integrated circuit (ASIC), which performs apredetermined function. However, the “unit does not always have ameaning limited to software or hardware. The “unit” may be constructedeither to be stored in an addressable storage medium or to execute oneor more processors. Therefore, the “unit” includes, for example,software elements, object-oriented software elements, class elements ortask elements, processes, functions, properties, procedures,sub-routines, segments of a program code, drivers, firmware,micro-codes, circuits, data, database, data structures, tables, arrays,and parameters. The elements and functions provided by the “unit” may beeither combined into a smaller number of elements, “unit” or dividedinto a larger number of elements, “unit”. Moreover, the elements and“units” may be implemented to reproduce one or more central processingunits (CPUs) within a device or a security multimedia card. Also, in anembodiment, the “˜ unit” may include one or more processors.

In the embodiments described in detail, main objects are a radio accessnetwork (new RAN, NR) and a core network, namely packet core (5G system,5G core network, or next generation core (NG Core)) in the 5G mobilecommunication standard specified by a mobile communication standardstandardization organization (3GPP). However, the main idea of thedisclosure is that the disclosure can be applied to other communicationsystems having a similar technical background, through a minormodification without deviating far from the range of the disclosure andthe application can be conducted by the determination of a person havingtechnical knowledge and skilled in the technical field to which thedisclosure belongs.

In a 5G system, in order to support the network automation, a networkdata collection and analysis function (NWDAF), which is a networkfunction of analyzing data collected in a 5G network and providing theanalyzed data, can be defined. The NWDAF can collect/store/analyzeinformation from/in/of the 5G network and provide a result for anunspecified network function (NF), and the analysis result can beindependently used in each NF.

Hereinafter, for convenience of description, a part of terms and names,which are defined in the 3rd generation partnership project long termevolution (3GPP LTE) standard such as a standard of 5G, NR, LTE, or asystem similar to these systems, can be used. However, the disclosure isnot limited by the terms and names, and may be equally applied to asystem that is based on another standard.

In addition, terms used below are illustrated for convenience ofdescription, for example, a term used to identify an access node, a termindicating network entities, a term indicating messages, a termindicating an interface between the network entities, a term indicatingvarious pieces of identification information, and the like. Accordingly,the disclosure is not limited to the following terms and other termshaving the same technical meaning can be used.

In order to meet wireless data traffic demands that have increased after4G communication system commercialization, efforts to develop animproved 5G communication system (new radio, NR) have been made. Inorder to achieve a high data transmission rate, the 5G communicationsystem is designed to support in a mmWave band (for example, 28 GHzfrequency band). In the 5G communication system, technologies such asbeamforming, massive MIMO, full dimensional MIMO (FD-MIMO), arrayantenna, analog beam-forming, and large scale antenna are beingdiscussed as a means to mitigate a propagation path loss in the mmWaveband and increase a propagation transmission distance. Unlike LTE, the5G communication system includes 15 kHz to support various subcarrierspacings such as 30 kHz, 60 kHz, and 120 kHz, and a physical controlchannel uses polar coding and a physical data channel uses low densityparity check (LDPC). As well as discrete fourier transform spreadorthogonal frequency-division multiplexing (DFT-S-OFDM), cyclic prefix(CP)-OFDM is used as a waveform for uplink transmission. LTE supportshybrid automatic repeat request (ARQ) (HARQ) retransmission based on atransport block (TB), whereas 5G can additionally support HARQretransmission based on a code block group (CBG) consisting of codeblocks (CB).

Further, the 5G communication system has developed technologies such asan evolved small cell, an advanced small cell, a cloud radio accessnetwork (cloud RAN), an ultra-dense network, device-to-device (D2D)communication, a wireless backhaul, a vehicle to everything (V2X)network, cooperative communication, coordinated multi-points (COMP), andreceived interference cancellation so as to improve the system network.

Meanwhile, the Internet has evolved from a human-oriented connectionnetwork in which humans generate and consume information to an internetof things (IoT) network in which distributed elements such as objectsexchange and process information. An internet of everything (IoE)technology in which a big data processing technology through aconnection with a cloud server or the like is combined with the IoTtechnology has emerged. In order to implement IoT, technical factorssuch as sensing technology, wired/wireless communication, networkinfrastructure, service-interface technology, and security technologyare required, and research on technologies such as a sensor network,machine-to-machine (M2M) communication, machine-type communication(MTC), and the like for connection between objects has recently beenconducted. In an IoT environment, through collection and analysis ofdata generated in connected objects, an intelligent internet technology(IT) service to create a new value for peoples' lives can be provided.The IoT can be applied to fields such as those of a smart home, a smartbuilding, a smart city, a smart car, a connected car, a smart grid,health care, a smart home appliance, and high-tech medical servicesthrough the convergence of the information technology (IT) of therelated art and various industries.

Accordingly, various attempts to apply the 5G communication system tothe IoT network have been made. For example, a technology such as asensor network, machine-to-machine (M2M) communication, and machine-typecommunication (MTC), has been implemented by the 5G communicationtechnology such as beamforming, MIMO, and array antennas. Theapplication of a cloud RAN as the big data processing technologydescribed above may be an example of convergence of a 3eG technology andthe IoT technology. Therefore, a plurality of services can be providedfor a user in a communication system, and in order to provide theplurality of services for the user, a method for providing each serviceaccording to characteristics within the same time section and anapparatus using this method are required. Research on various services,which are provided in the 5G communication system, has been conducted,and one of the services is a service satisfying requirements such as lowlatency and high reliability.

In a case of vehicle communication, a standardization operation ofLTE-based V2X has been completed at 3GPP Rel-14 and Rel-15, based on adevice-to-device (D2D) communication structure, and efforts to developV2X, based on 5G NR, have been currently made. NR V2X will supportunicast communication, groupcast (or multicast) communication, andbroadcast communication between UEs. In addition, unlike LTE V2X whosepurpose is to transmit or receive basic safety information required forvehicle road driving, NR V2X has a purpose of providing further advancedservices such as platooning, advanced driving, extended sensor, andremote driving.

When an NR V2X UE exists within the coverage of a base station, the NRV2X UE may receive, from the base station, parameter values forcontrolling sidelink transmission power, and control sidelinktransmission power, based on the parameter values. In addition, when theNR V2X UE exists out of the coverage of the base station, the NR V2X UEmay use preset sidelink transmission power control parameter values tocontrol sidelink transmission power. The sidelink transmission powercontrol parameters may include P₀ and α. In addition, the NR V2X UE mayset a transmission power value according to frequency block size of asidelink control channel and a data channel to be transmitted thereby,as well as the values of P₀ and α mentioned above. That is, when thefrequency block size of a sidelink control channel and a data channel tobe transmitted increases, the transmission power value may increase, andwhen the frequency block size decreases, the transmission power valuemay decrease. A sidelink control channel and a data channel may betime-division-multiplexed (TDMed) on the time axis orfrequency-division-multiplexed (FDMed) on the frequency axis, beforebeing transmitted. Therefore, a method and an apparatus for controllingUE transmission power to support sidelink transmission power in thesevarious multiplexing methods are required.

An embodiment of the specification is proposed to support the variousmultiplexing methods described above, and a purpose is to provide amethod and an apparatus for controlling transmission powers of asidelink control channel and a data channel.

A V2X UE mentioned in the disclosure may indicate an NR V2X UE or an LTEV2X UE. In addition, the V2X UE of the disclosure may indicate a vehiclesupporting vehicle-to-vehicle (V2V) communication, a vehicle or apedestrian's handset (that is, smartphone) supportingvehicle-to-pedestrian (V2P) communication, a vehicle supportingvehicle-to-network (V2N) communication, or a vehicle supportingvehicle-to-infrastructure (V2I) communication. In addition, a UE of thedisclosure may indicate a road side unit (RSU) having a UE function, anRSU having a base station function, or an RSU having a part of a basestation function and a part of a UE function.

FIG. 1A illustrates a system according to an embodiment of thedisclosure, FIG. 1B illustrates a system according to an embodiment ofthe disclosure, FIG. 1C illustrates a system according to an embodimentof the disclosure, and FIG. 1D illustrates a system according to anembodiment of the disclosure.

FIG. 1A illustrates a case in which all V2X UEs (UE-1 101 and UE-2 102)are positioned within the coverage of a base station 103.

Referring to FIG. 1A, all the V2X UEs 101 and 102 may receive, from thebase station 103, data and control information via downlink (DL), ortransmit, to the base station 103, data and control information viauplink (UL). The data and control information may be data and controlinformation for V2X communication, or the data and control informationmay be data and control information for general cellular communication.In addition, the V2X UEs 101 and 102 may transmit or receive data andcontrol information for V2X communication via sidelink (SL).

FIG. 1B illustrates a case in which among V2X UEs, a UE-1 111 ispositioned within the coverage of a base station 113 and a UE-2 112 ispositioned out of the coverage of the base station 113. FIG. 1B mayillustrate partial coverage. The UE-1 111 positioned within the coverageof the base station 113 may receive, from the base station 113, data andcontrol information via downlink, or transmit, to the base station, dataand control information via uplink.

Referring to FIG. 1B, the UE-2 112 positioned out of the coverage of thebase station may not receive, from the base station, data and controlinformation via downlink, and may not transmit, to the base station,data and control information via uplink.

The UE-2 112 may transmit/receive data and control information for V2Xcommunication to/from the UE-1 111 via sidelink.

FIG. 1C illustrates a case in which all V2X UEs are positioned out ofthe coverage of a base station.

Therefore, referring to FIG. 1C, a UE-1 121 and a UE-2 122 may notreceive, from a base station, data and control information via downlink,and may not transmit, to the base station, data and control informationvia uplink.

The UE-1 121 and the UE-2 122 may transmit or receive data and controlinformation for V2X communication via sidelink.

FIG. 1D illustrates a scenario of performing V2X communication betweenUEs positioned in different cells. Specifically, FIG. 1D illustrates acase in which a V2X transmission UE and a V2X reception UE accessdifferent base stations (radio resource control (RRC) connection state)or camp on different base stations (RRC disconnection state, that is,RRC idle state). A UE-1 131 may be a V2X transmission UE and a UE-2 132may be a V2X reception UE, or the UE-1 131 may be a V2X reception UE andthe UE-2 132 may be a V2X transmission UE. The UE-1 131 may receive,from a base station 133 which the UE-1 accesses (or on which the UE-1camps), a V2X exclusive system information block (SIB), and the UE-2 132may receive, from another base station 134 which the UE-2 accesses (oron which the UE-2 camps), a V2X exclusive SIB. Information of the V2Xexclusive SIB which the UE-1 131 receives and information of the V2Xexclusive SIB which the UE-2 132 receives may differ from each other.Therefore, in order to perform V2X communication between UEs positionedin different cells, pieces of information are required to be unified.

FIGS. 1A to 1D illustrate a V2X system constituted by two UEs (UE-1 andUE-2) for convenience of description, but the disclosure is not limitedthereto. In addition, uplink and downlink between a base station and V2XUEs may be called an Uu interface, and sidelink between V2X UEs may becalled a PC5 interface. Therefore, they can be mixedly used in thedisclosure.

Meanwhile, the UE of the disclosure may indicate a vehicle supportingvehicle-to-vehicle (V2V) communication, a vehicle or a pedestrian'shandset (that is, smartphone) supporting vehicle-to-pedestrian (V2P)communication, a vehicle supporting vehicle-to-network (V2N)communication, or a vehicle supporting vehicle-to-infrastructure (V2I)communication. In addition, the UE of the disclosure may indicate a roadside unit (RSU) having a UE function, an RSU having a base stationfunction, or an RSU having a part of a base station function and a partof a UE function.

In addition, the base station of the disclosure may be previouslydefined as a base station supporting both V2X communication and generalcellular communication or a base station supporting only V2Xcommunication. The base station may indicate a 5G base station (gNB), a4G base station (eNB), or a road site unit (RSU). Therefore, unlessotherwise specified in the disclosure, a base station and an RSU can bemixedly used as the same concept.

FIG. 2A illustrates a V2X communication method performed via sidelinkaccording to an embodiment of the disclosure, and FIG. 2B illustrates aV2X communication method performed via sidelink according to anembodiment of the disclosure.

Referring to FIG. 2A, a TX UE (a UE-1 201) and an RX UE (a UE-2 202) mayperform one-to-one communication, and this communication may be calledunicast communication.

Referring to FIG. 2B, a TX UE and an RX UE may perform one-to-manycommunication, and this communication may be called groupcast ormulticast communication.

FIG. 2B is a diagram illustrating that a UE-1 211, a UE-2 212, and aUE-3 213 form group A to perform groupcast communication, and a UE-4214, a UE-5 215, a UE-6 216, and a UE-7 217 form group B to performgroupcast communication. Each of the UEs performs groupcastcommunication within a group to which each of the UEs belongs, andcommunication between different groups is not performed. FIG. 2Billustrates that two groups are formed, but the disclosure is notlimited thereto.

Although not shown in FIGS. 2A and 2B, V2X UEs may perform broadcastcommunication. The broadcast communication indicates a case in which allV2X UEs receive data and control information that a V2X transmission UEtransmits via sidelink. For example, assuming that in FIG. 2B, the UE-1is a transmission UE for broadcast communication, all the UEs (UE-2 212,UE-3 213, UE-4 214, UE-5 215, UE-6 216, and UE-7 217) may receive dataand control information that the UE-1 211 transmits.

FIG. 3 illustrates V2X transmission power control according to anembodiment of the disclosure.

Referring to FIG. 3, it is assumed that a UE1 301 is positioned close toa base station (gNB) 303, and a UE2 302 is positioned far from the gNB303 (that is, the UE 1 is positioned at the cell center and the UE2 ispositioned at the cell edge). When the UE1 301 and the UE2 302 performV2X communication therebetween, it is assumed that the UE1 301 is a V2Xtransmission UE and the UE2 302 is a V2X reception UE. The UE1 301 mayperform sidelink transmission power control for V2X transmission.Parameters for sidelink transmission power of the UE1 301 may include atleast P₀, α, an estimated path loss value, and the size of an allocatedfrequency block, and may be equal to what shown in Equation 1.

Sidelink transmission power=min{Pcmax,P ₀ +αPL+10 log 10(Number ofRBs*2^(μ))+Δ}[dBm]  Equation 1

In Equation 1, each parameter may indicate the following.

-   -   Pcmax: Pcmax is a P-max value (when there is no base station, a        preset value) indicating the maximum UE transmission output and        set by a base station through system information or RRC, and may        be determined by a UE by means of UE power class included in the        UE.    -   P₀: P₀ may indicate a value (when there is no base station, a        preset value) set by a base station through system information        or RRC in order to guarantee link quality of a reception UE.

α: α is a parameter for compensating a path loss value and has a valuebetween 0 and 1, and may indicate a value (when there is no basestation, a preset value) set by a base station through systeminformation or RRC. For example, when α=1, 100% of path loss may becompensated, and when α=0.8, only 80% of path loss may be compensated.

-   -   Number of resource blocks (RBs): Number of RBs may indicate size        of a frequency block allocated for sidelink transmission. 2^(μ)        may be a parameter for compensating a power spectral density        (PSD) which varies depending on a subcarrier spacing. For        example, a case of using a subcarrier spacing of 15 kHz may        indicate that μ=0. Even if the same number of frequency blocks        are used, when the subcarrier spacing is doubled to 30 kHz, the        PSD may be reduced by half compared with the case of using the        subcarrier spacing of 15 kHz. Therefore, in order to compensate        the PSD, power is required to be doubled. More specifically, for        example, when two frequency blocks are used, 10 log 10(2×2⁰)=3        dB is required for the subcarrier spacing of 15 kHz, whereas, in        order to maintain the same PSD as that for the subcarrier        spacing of 15 kHz, transmission power is required to be        increased to 10 log 10(2×2¹)=6 dB for the subcarrier spacing of        30 kHz.    -   PL: PL may indicate an estimated path loss value. The path loss        value may be estimated by Equation 2.

The transmission power of a signal used for path loss estimation−Themeasured reference signal received power (RSRP) value of a signal usedfor path loss estimation   Equation 2

Equation 2 may be differently applied depending on a scenario asfollows.

-   -   When a signal used for path loss estimation is a sidelink        signal: the UE1 301, which is a V2X transmission UE, may        transmit a sidelink synchronization signal or a sidelink        reference signal to the UE2 302 which is a V2X reception UE. The        UE2 302 may receive the sidelink synchronization signal or the        sidelink reference signal to measure an RSRP value and report        the measured RSRP value to the UE1 301. The RSRP value may be        transmitted through a physical sidelink feedback channel (PSFCH)        or a physical sidelink shared channel (PSSCH). In addition, when        the RSRP value is transmitted through the PSSCH, a media access        control (MAC) control element (CE) may be used. The UE1 301 may        estimate a sidelink path loss value by using Equation 2 through        the transmission power of a reference signal that the UE1        transmits to the UE2 302 and the RSRP value reported from the        UE2 302. In another example, the UE1 301 may transmit, to the        UE2 302, information on the transmission power of the reference        signal that the UE1 transmits. Upon receiving the information,        the UE2 302 may measure the RSRP value by using the reference        signal that the UE1 transmits, and estimate a path loss value        through Equation 2. The UE2 302 may transmit an estimated        sidelink path loss value to the UE1 301 through the PSFCH or the        PSSCH. When the estimated sidelink path loss value is        transmitted through the PSSCH, the MAC CE may be used. However,        as illustrated in FIG. 3, when a distance between the UE1 301        and the UE2 302 is farther than a distance between the UE1 301        and the gNB 303, a sidelink signal that the UE1 301 transmits        may cause interference to a gNB reception signal.

FIG. 4 illustrates interference caused by a frequency block transmittedby a V2X UE in an adjacent frequency block according to an embodiment ofthe disclosure.

FIG. 5 illustrates interference caused by a frequency block transmittedby a V2X UE in an adjacent frequency block according to an embodiment ofthe disclosure.

FIGS. 4 and 5 illustrate a degree of interference caused by a sidelinksignal in a gNB reception signal. Referring to FIG. 4, it is assumedthat sidelink control information or data information is transmitted inresource block index 12 (one resource block is used), and referring toFIG. 5, it is assumed that sidelink control information or datainformation is transmitted by using five resource blocks from resourceblock index 12 to 17. Referring to FIG. 4, since sidelink transmissionis performed only in resource block index 12, transmission power shouldbe generated only in the corresponding resource index, but it is foundthat due to interference (in-band emission), transmission power isgenerated even in neighboring resource indices (for example, index 9,10, 11, 13, 14, and 15). It is found that as illustrated in FIG. 5, suchinterference volume becomes bigger as the number of resource blocksallocated for sidelink transmission increases. Therefore, a V2X UEpositioned close to the gNB is required to use low transmission powernot to cause interference to a reception signal of the gNB.

-   -   When a signal used for path loss estimation is a downlink signal        of the gNB: in order to reduce the interference caused to the        reception signal of the gNB, the UE1, which is a V2X        transmission UE, may apply a downlink path loss value of the gNB        to Equation 1. More specifically, a downlink path loss value may        be estimated by the UE 1 through a channel state information        (CSI)-reference signal (RS) that the gNB transmits. In another        example, the UE1 may use a secondary synchronization signal        (SSS) that the gNB transmits, or both the SSS and a demodulation        reference signal (DMRS) transmitted through a physical broadcast        channel (PBCH) to estimate a downlink path loss value. More        specifically, the gNB may transmit, to the UE1, information on        transmission power of a reference signal through system        information or RRC configuration, and the UE1 may measure an        RSRP value by using the reference signal transmitted by the gNB.        The UE1 may estimate a downlink path loss value by using        Equation 2 through a transmission power value of the reference        signal transmitted from the base station and the RSRP value        measured thereby. As the downlink path loss value is used, as        illustrated in FIGS. 4 and 5, the interference problem, which is        caused to the reception signal of the gNB, can be solved.

FIG. 6 illustrates V2X transmission power control according to anembodiment of the disclosure.

Referring to FIG. 6, in a case in which V2X UEs 601 and 602 arepositioned close to each other, but positioned far from a gNB 603, whena downlink path loss value is used, unnecessary power consumption andinterference in adjacent V2X UEs may be caused. Therefore, both methodsabove may be required.

-   -   That is, the gNB may configure which reference signal is used by        a UE to estimate path loss (PL) in Equation 1 (that is, whether        to use an SSS or a CSI-RS for estimating downlink path loss or        whether to use a sidelink reference signal for estimating        sidelink path loss).    -   Δ: Δ may indicate a transmit power control (TPC) command for        closed-loop power control, or other RRC parameter. For example,        Δ may indicate an offset value of transmission power according        to a format of a sidelink control channel or a sidelink data        channel. In another example, A may indicate a compensation value        of transmission power depending on a spectral efficiency of a        sidelink control channel or a sidelink data channel. That is,        since as the spectral efficiency becomes higher (that is, a case        of using less resources to transmit the same bit or a case of        transmitting more bits by using the same amount of resources),        the higher transmission power is required to be used, Δ may be a        parameter which compensates a transmission power value depending        on a spectral efficiency. In Equation 1, Δ is illustrated to be        constituted by a single parameter, but may be constituted by a        combination of the two or more parameters previously        illustrated.

FIG. 7 is a diagram illustrating a sidelink resource for, by a V2X UE,performing V2X communication according to an embodiment of thedisclosure.

Referring to FIG. 7, a sidelink resource may be constituted by K symbolson the time axis and be constituted by M resource blocks (RB) on thefrequency axis. One resource block may be constituted by twelvesub-carriers. The K symbols may be physically continuous or logicallycontinuous on the time axis (in a case of being logically continuous,the symbols may be physically discontinuous). Similarly, the M resourceblocks may be physically continuous or logically continuous on thefrequency axis (in a case of being logically continuous, the blocks maybe physically discontinuous). Although not shown in FIG. 7, a V2Xtransmission UE may use the sidelink resource of FIG. 7 to transmitsidelink control information or data information. In addition, a V2Xreception UE may use the sidelink resource of FIG. 7 to receive sidelinkcontrol information or data information. In another example, a V2Xreception UE may use the sidelink resource of FIG. 7 to transmitsidelink feedback information to a V2X transmission UE. Referring toFIG. 7, values of K and M may be identical or vary depending on the timewhen sidelink control information or data information is transmitted.For example, when a V2X transmission UE transmits sidelink controlinformation (or sidelink data information) at the time of T1, the valuesof K and M may be equal to or different from the values of K and M whena V2X transmission UE transmits sidelink control information (orsidelink data information) at the time of T2. Similarly, referring toFIG. 7, the values of K and M may be identical or vary depending on thetime when a V2X reception UE receives sidelink control information ordata information. For example, when a V2X reception UE receives sidelinkcontrol information (or sidelink data information) at the time of T1,the values of K and M may be equal to or different from the values of Kand M when a V2X reception UE receives sidelink control information (orsidelink data information) at the time of T2. In addition, referring toFIG. 7, the values of K and M may be identical or vary depending on thetime when a V2X reception UE transmits sidelink feedback information toa V2X transmission UE. For example, when a V2X reception UE transmitssidelink feedback information to a V2X transmission UE at the time ofT1, the values of K and M may be equal to or different from the valuesof K and M when a V2X reception UE transmits sidelink feedbackinformation to a V2X transmission UE at the time of T2.

FIG. 8 illustrates a multiplexing method of a sidelink control channeland a sidelink data channel within a sidelink resource according to anembodiment of the disclosure.

Referring to FIG. 8, multiplexing of a physical sidelink control channel(PSCCH) and a physical sidelink shared channel (PSSCH) on the time axis,that is, time division multiplexing (TDM) is illustrated. A PSCCH and aPSSCH may be constituted by the same number of resource blocks (M RBs)on the frequency axis, and may be constituted by K1 symbols and K2symbols, respectively, on the time axis. Values of K1 and K2 may beequal to or different from each other. In addition, when the values ofK1 and K2 are different from each other, the values may be K1>K2 orK1<K2. The V2X transmission UE may transmit sidelink control information(SCI) including time/frequency allocation information of the PSSCH,through the PSCCH. The V2X reception UE may receive and decode thePSCCH, and then may acquire the time/frequency allocation information ofthe PSSCH and decode the PSSCH. FIG. 8 illustrates the PSSCH constitutedby the K2 symbols, which is physically continuously positioned after thePSCCH constituted by the K1 symbols, although they may not be physicallycontinuously positioned (that is, the PSSCH may be logicallycontinuously positioned without being physically continuously positionedafter the PSCCH). In addition, although not shown in FIG. 8, a physicalsidelink feedback channel (PSFCH) may exist within a sidelink resourceconstituted by K symbols. The PSCCH may be constituted by the K1symbols, the PSSCH may be constituted by the K2 symbols and a guardsymbol, and the PSFCH may be constituted by K3 symbols, and K1+K2+ thenumber of guard symbols+K3 may be smaller than K. The guard symbol maybe one or at least two OFDM symbols. The V2X reception UE may decode thePSSCH, and then may transmit the PSFCH including the result (that is,ACK/NACK information) to the V2X transmission UE.

At the i-th transmission time, the V2X UE using a sidelink resourcestructure of FIG. 8 may determine each of transmission power (P_(PSSCH))of the PSCCH and transmission power (P_(PSSCH)) of the PSSCH throughEquation 3.

P _(PSSCH)(i)=min{Pcmax(i),P _(0_PSCCH) +αP _(SCCH) *PL(q)+10 log10(M*2^(μ))+Δ_(PSSCH)(i)}[dBm]

P _(PSSCH)(i)=min{Pcmax(i),P _(0_PSSCH) +αP _(SSCH) *PL(q)+10 log10(M*2^(μ)+Δ_(PSSCH)(i)}[dBm]   Equation 3

In Equation 3, each parameter may indicate the following.

-   -   Pcmax(i): Pcmax(i) is a P-max value (when there is no base        station, a preset value) indicating the maximum UE transmission        output at the i-th transmission time and set by a base station        through system information or RRC, and may be determined by a UE        by means of a communication range and UE power class included in        the UE. Since Pcmax(i) is a function of index “i”, different        transmission times may result in different Pcmax values.    -   P_(0_PSCCH), P_(0_PSSCH): P_(0_PSCCH) and P_(0_PSSCH) may        indicate parameters (when there is no base station, preset        values) set by a base station through system information or RRC        in order to guarantee link quality of each of the PSCCH and the        PSSCH. Values of P_(0_PSCCH) and P_(0_PSSCH) may be different        from each other according to a sidelink scheduling method. For        example, a gNB may schedule a sidelink transmission resource to        the V2X transmission UE through downlink control information        (DCI). It may be called a mode-1 resource allocation method. In        another scheduling method, the gNB may configure resource pool        information for sidelink transmission, and may determine a        resource required for the V2X transmission UE to transmit        sidelink control information and data information by itself. It        may be called a mode-2 resource allocation method. Since in a        case of mode-1, the gNB may manage a resource in a centralized        manner, the gNB may control interference and resource collision        problems between different V2X UEs. On the other hand, in a case        of mode-2, since UEs manage a resource in a distributed manner,        interference and resource collision problems between different        V2X UEs may occur as compared to mode-1. Therefore, values of P₀        for sidelink transmission of mode-1 and mode-2 may be different.        That is, P_(0_PSCCH) for mode-1 and P_(0_PSCCH) for mode-2 have        different values. In addition, P_(0_PSSCH) for mode-1 and        P_(0_PSSCH) for mode-2 have different values. In another        example, as illustrated in FIGS. 2A and 2B, V2X UEs may perform        V2X communication by using one of unicast, groupcast, and        broadcast communication methods. Different link qualities may be        required according to a communication method. For example, in a        case of unicast communication, since a hybrid automatic repeat        request (HARQ) ACK/NACK transmission is possible through a        sidelink feedback channel, and the degradation of link quality        may be reduced. However, in a case of broadcast communication,        since sidelink feedback transmission is impossible, higher link        quality may be required as compared to the unicast        communication. Therefore, values of P_(0_PSCCH) and P_(0_PSSCH)        may be different from each other according to communication        methods including unicast, groupcast, and broadcast        communication methods. As mentioned above, the values of        P_(0_PSCCH) and P_(0_PSSCH) may be transmitted by a base station        to a UE through system information or RRC configuration, or may        be preset values when there is no base station. Therefore, the        base station may not recognize a V2X communication method        (unicast/groupcast/broadcast) that a sidelink UE is to transmit.        The base station may not know when the UE should use values of        P_(0_PSCCH) and P_(0_PSSCH) and which values of P_(0_PSCCH) and        P_(0_PSSCH) should be used. In order to solve these problems,        following operations can be assumed. One or more different        associated resource pools for each communication method may        exist. For example, the base station may configure, to the UE,        one or more resource pools (for example, resource pool 1,        resource pool 2) for unicast communication, one or more resource        pools (for example, resource pool 3, resource pool 4) for        groupcast communication, and one or more resource pools (for        example, resource pool 5, resource pool 6) for broadcast        communication. The values of P_(0_PSCCH) and P_(0_PSSCH) may        vary depending on a resource pool. In another example,        P_(0_PSCCH) may be constituted by P_(0_PSCCH1) and P_(0_PSCCH2),        and P_(0_PSSCH) may be constituted by P_(0_PSSCH1) and        P_(0_PSSCH2). All UEs within a cell may receive the same set        value with respect to P_(0_PSCCH1) and P_(0_PSSCH1). Different        V2X UEs within one cell may receive different set values with        respect to P_(0_PSCCH2) and P_(0_PSSCH2). In the above example,        P_(0_PSCCH1) and P_(0_PSSCH1) may be irrelevant to the        communication type (that is, the same value is applied to the        unicast, groupcast, broadcast communications), and P_(0_PSCCH2)        and P_(0_PSSCH2) may vary depending on the communication type.    -   α_(PSCCH), α_(PSSCH): α_(PSCCH) and α_(PSSCH) are parameters for        compensating path loss values of the PSCCH and the PSSCH,        respectively, have values between 0 and 1, and may indicate        values set by a base station through system information or RRC        (when there is no base station, a preset value). For example,        when α=1, 100% of path loss may be compensated, and when α=0.8,        only 80% of path loss may be compensated. As in P_(0_PSCCH) and        P_(0_PSSCH) illustrated above, α_(PSCCH) for mode-1 and        α_(PSCCH) for mode-2 may have different values. In addition,        α_(PSSCH) for mode-1 and α_(PSSCH) for mode-2 may have different        values. Also, values of α_(PSCCH) and α_(PSSCH) may be set to        vary depending on communication methods including the unicast,        groupcast, and broadcast communication methods. To this end,        α_(PSCCH) and α_(PSSCH) may have different values for each        resource pool.    -   M: M may indicate the size of a frequency block allocated for        sidelink transmission. Referring to FIG. 8, since both the PSCCH        and the PSSCH use M frequency blocks, and the value of 10 log        10(M2^(μ)) may be used in Equation 3. 2^(μ) may be a parameter        for compensating a power spectral density (PSD) which vary        depending on a subcarrier spacing. For example, a case of using        a subcarrier spacing of 15 kHz may indicate that μ=0. Even if        the same number of frequency blocks are used, when the        subcarrier spacing is doubled to 30 kHz, the PSD may be reduced        by half compared with the case of using the subcarrier spacing        of 15 kHz. Therefore, in order to compensate the PSD, power is        required to be doubled. More specifically, for example, when two        frequency blocks are used, 10 log 10(2×2⁰)=3 dB is required for        the subcarrier spacing of 15 kHz, whereas, in order to maintain        the same PSD as that for the subcarrier spacing of 15 kHz,        transmission power is required to be increased to 10 log        10(2×2¹)=6 dB for the subcarrier spacing of 30 kHz.

PL(q): PL(q) may indicate an estimated path loss value. The path lossvalue may be estimated by Equation 2. The index “q” may indicate anindex of a reference signal used for path loss estimation. For example,when q=0, the V2X transmission UE may use an SSS that the gNB transmits,or an SSS and a DMRS transmitted through a PBCH in order to estimate thepath loss value in Equation 3. When q=1, the V2X transmission UE may usea CSI-RS transmitted by the gNB in order to estimate the path loss valuein Equation 3. When q=2, the V2X transmission UE may use a sidelinkreference signal in order to estimate the path loss value in Equation 3.When path loss of Equation 3 is estimated by using the sidelinkreference signal, one of the two methods mentioned in FIG. 3 may beused. That is, there are a method in which the V2X reception UEestimates sidelink path loss and transmits a result to the V2Xtransmission UE, and a method in which the V2X transmission UE uses RSRPhaving been measured and reported by the V2X reception UE to estimatesidelink path loss. The reference signal index “q” may be associatedwith each resource pool. That is, different resource pools may setdifferent reference signal indices and the UE receiving the set indicesmay determine the application of downlink path loss with the basestation or the application of sidelink path loss.

-   -   As mentioned above, upon receiving, from the base station,        resource pool information, through system information and RRC        configuration, the V2X UE may use P_(0_PSCCH), P_(0_PSSCH),        α_(PSCCH), α_(PSSCH), and index information of a reference        signal for path loss estimation, which are included in the        resource pool information, and thus set transmission power        values of the PSCCH and the PSSCH through Equation 3.    -   Δ_(PSSCH), Δ_(PSSCH): Δ_(PSCCH) and Δ_(PSSCH) may indicate TPC        commands for closed-loop power control, or other RRC parameters.        For example, Δ_(PSSCH) and Δ_(PSSCH) may indicate offset values        of transmission power according to a format of a sidelink        control channel or a sidelink data channel. In another example,        Δ_(PSCCH) and Δ_(PSSCH) may indicate compensation values of        transmission power according to a spectral efficiency of a        sidelink control channel or a sidelink data channel. That is,        since as the spectral efficiency becomes higher (that is, a case        of using less resources to transmit the same bit or a case of        transmitting more bits by using the same amount of resources),        the higher transmission power is required to be used, Δ_(PSCCH)        and Δ_(PSSCH) may be parameters which compensate transmission        power values depending on a spectral efficiency. In Equation 3,        Δ_(PSCCH) and Δ_(PSSCH) are illustrated to be constituted by a        single parameter, but may be constituted by a combination of the        two or more parameters previously illustrated. In another        example, when closed-loop power control is not operated at        sidelink, Δ_(PSCCH) and Δ_(PSSCH) may be omitted from Equation        3.    -   In the above example, UEs existing out of the coverage of the        base station may not receive, from the base station, setting        with respect to P_(0_PSCCH), α_(PSCCH), Δ_(PSCCH), and        P_(0_PSSCH), α_(PSSCH), Δ_(PSSCH) parameters. Therefore, these        UEs may use preset values with respect to the parameters. The        preset values may include 0, 0 dB, or 0 dBm. The preset value        may indicate a value input in a UE in the factory, or when the        UE has existed within the coverage of the base station (the UE        is positioned out of the coverage of the base station now), may        indicate a value set by the base station.    -   In addition, in the above example, even though UEs exist within        the coverage of the base station, exchange of parameters between        the UEs may not be performed (assuming that exchange of        parameters between the UEs is performed in a PC5 RRC layer) when        a UE pairing for performing unicast communication is not formed        (for example, before PC5 RRC configuration is completed in a PC5        RRC layer of UE A and UE B), or before a UE grouping for        performing groupcast communication is formed. A transmission UE        for the unicast and groupcast communications may not set a        transmission power value based on sidelink path loss        measurement. Therefore, like the mentioned method, the preset        value may be used, or the values of P_(0_PSCCH), α_(PSCCH),        Δ_(PSCCH) and P_(0_PSSCH), α_(PSSCH), Δ_(PSSCH), which are        transmitted from the base station through RRC configuration and        system information of the base station, may be used. The values        of P_(0_PSCCH), α_(PSCCH), Δ_(PSCCH) and P_(0_PSSCH), α_(PSSCH),        Δ_(PSSCH) which are used at this time may be different from the        values of P_(0_PSCCH), α_(PSCCH), Δ_(PSCCH) and P_(0_PSSCH),        α_(PSSCH), Δ_(PSSCH) which are used after PCT RRC configuration.        PL(q) that the transmission UE uses in Equation 3 before PC5 RRC        configuration may indicate a path loss value with respect to Uu        link between the base station and the transmission UE, not the        sidelink path loss value.    -   In another example, when in the example above, the PSCCH, the        PSSCH, and the PSFCH should be transmitted before PC5 RRC        configuration between UEs, which are to perform the unicast or        groupcast communication, is completed, the V2X UE may use the        preset transmission power value (for example, [X] dBm) or the        transmission power value set by the base station. The        transmission power values preset for transmitting the PSCCH, the        PSSCH, and the PSFCH (or the transmission power values set by        the base station) may be different from each other.    -   In another example, the preset transmission power values or the        transmission power values set by the base station, of the PSCCH,        the PSSCH, and the PSFCH may be expressed as the transmission        power value and the offset value with respect to one channel.        For example, when the transmission power values of the PSCCH,        the PSSCH, and the PSFCH are preset, the transmission power        value of the PSCCH may be set to be [X] dBm, and the offset        value for transmission power of the PSSCH and the PSFCH may be        set to be +/−[Y] dB (or dBm), based on the transmission power        value of the PSCCH. It may be equally applied even when the        transmission power values of the PSCCH, the PSSCH, and the PSFCH        are set by the base station.

FIG. 9 illustrates a multiplexing method of a sidelink control channeland a sidelink data channel within a sidelink resource according to anembodiment of the disclosure.

Referring to FIG. 9, FIG. 9 illustrates that a PSCCH and a PSSCH aretime-division-multiplexed, but unlike FIG. 8, illustrates that the PSCCHand the PSSCH are constituted by different numbers of resource blocks onthe frequency axis. That is, on the frequency axis, the PSCCH may beconstituted by N1 frequency blocks, and the PSSCH may be constituted byM frequency blocks. N1 may be smaller than M (N1<M). Meanwhile, similarto FIG. 8, on the time axis, the PSCCH may be constituted by K1 symbols,and the PSSCH may be constituted by K2 symbols. The values of K1 and K2are equal to or different from each other. In addition, when the valuesof K1 and K2 are different from each other, the values may be K1>K2 orK1<K2. The V2X transmission UE may transmit sidelink control information(SCI) including time/frequency allocation information of the PSSCHthrough the PSCCH. The V2X reception UE may receive and decode thePSCCH, and then may acquire the time/frequency allocation information ofthe PSSCH and decode the PSSCH. FIG. 9 illustrates the PSSCH constitutedby the K2 symbols, which is physically continuously positioned after thePSCCH constituted by the K1 symbols, although they may not be physicallycontinuously positioned (that is, the PSSCH may be logicallycontinuously positioned without being physically continuously positionedafter the PSCCH). In addition, although not shown in FIG. 9, a PSFCH mayexist within a sidelink resource constituted by K symbols. The PSCCH maybe constituted by the K1 symbols, the PSSCH may be constituted by the K2symbols and a guard symbol, and the PSFCH may be constituted by K3symbols, and K1+K2+ the number of guard symbols+K3 may be equal to orsmaller than K. The guard symbol may be one or at least two OFDMsymbols. In addition, on the frequency axis of the PSFCH, the size ofresource blocks may be equal to or different from the size of resourceblocks of the PSCCH and the PSSCH. The V2X reception UE may decode thePSSCH, and then transmit the PSFCH including the result (that is,ACK/NACK information) to the V2X transmission UE.

At the i-th transmission time, the V2X UE using a sidelink resourcestructure of FIG. 9 may determine each of transmission power (P_(PSSCH))of the PSCCH and transmission power (P_(PSSCH)) of the PSSCH throughEquation 4.

P _(PSSCH)(i)=min{Pcmax(i),P _(0_PSCCH)+α_(PSCCH) *PL(q)+10 log10(N1*2^(μ))+Δ_(PSSCH)(i)}[dBm]

P _(PSSCH)(i)=min{Pcmax(i),P _(0_PSSCH)+α_(PSSCH) *PL(q)+10 log10(M*2^(μ))+Δ_(PSSCH)(i)}[dBm]  Equation 4

In Equation 4, each parameter may be interpreted to be the same asEquation 3 illustrated in FIG. 8. Equation 4 differs from Equation 3 inthat the size of frequency blocks allocated for the PSCCH is different.That is, it is illustrated that in Equation 4, N1 frequency blocks areused, and in Equation 3, M frequency blocks are used.

A definition and a method of use of parameters including P_(0_PSCCH),α_(PSCCH), Δ_(PSCCH) and P_(0_PSSCH), α_(PSSCH), Δ_(PSSCH) which areused in Equation 4 may be equal to the definition and the embodimentdescribed in Equation 3 of FIG. 8. For example, the transmission powerparameters used in Equation 4 may use a set value that the transmissionUE receives from the base station or use a value preset to the UE bymeans of the methods mentioned in FIGS. 8 and 9. For example, the UEsexiting out of the coverage of the base station may not receive, fromthe base station, setting with respect to transmission power parameters.Therefore, these UEs may use preset values with respect to theparameters. The set values may include 0, 0 dB, or 0 dBm. The presetvalue may indicate a value input in a UE in the factory or when the UEhas existed within the coverage of the base station (the UE ispositioned out of the coverage of the base station now), may indicate avalue set by the base station.

In another example, even though UEs exist within the coverage of thebase station, exchange of parameters between UEs may not be performed(assuming that exchange of parameters between the UEs is performed in aPC5 RRC layer) when a UE pairing for performing unicast communication isnot formed (for example, before PC5 RRC configuration is completed in aPC5 RRC layer of UE A and UE B), or before a UE grouping for performinggroupcast communication is formed. A transmission UE for the unicast andgroupcast communications may not set a transmission power value based ona sidelink path loss signal. To this end, the preset value with respectto the mentioned parameters may be used, or the value transmitted fromthe base station through RRC configuration and system information of thebase station may be used. The values of the parameters used at this timemay be different from the values of the parameters used after PC5 RRCconfiguration. PL(q) that the transmission UE uses before PC5 RRCconfiguration in Equation 7, Equation 8, Equation 9, Equation 10, andEquation 11 may indicate a path loss value with respect to Uu linkbetween the base station and the transmission UE, not the sidelink pathloss value. In addition, when the UE uses the preset parameters, each ofthe parameters may include the value of 0, 0 dB, or 0 dBm.

In another example, when in the example above, the PSCCH, the PSSCH, andthe PSFCH should be transmitted before PC5 RRC configuration betweenUEs, which are to perform the unicast or groupcast communication, iscompleted, the V2X UE may use the preset transmission power value (forexample, [X] dBm) or the transmission power value set by the basestation. The transmission power values preset for transmitting thePSCCH, the PSSCH, and the PSFCH (or the transmission power values set bythe base station) may be different from each other.

In another example, the preset transmission power values or thetransmission power values set by the base station, of the PSCCH, thePSSCH, and the PSFCH may be expressed as the transmission power valueand the offset value with respect to one channel. For example, when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH arepreset, the transmission power value of the PSCCH may be set to be [X]dBm, and the offset value for transmission power of the PSSCH and thePSFCH may be set to be +/−[Y] dB (or dBm), based on the transmissionpower value of the PSCCH. It may be equally applied even when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH are setby the base station.

FIG. 10 illustrates a V2X frame structure according to an embodiment ofthe disclosure.

Referring to FIG. 10, unlike FIGS. 8 and 9, illustrates that a PSCCH anda PSSCH are frequency-division-multiplexed on the frequency axis, andsimilar to FIG. 9, illustrates that the PSCCH and the PSSCH areconstituted by different numbers of resource blocks. That is, on thefrequency axis, the PSCCH may be constituted by N1 frequency blocks andthe PSSCH may be constituted by M frequency blocks, and on the timeaxis, the PSCCH and the PSSCH may be constituted by the same number ofsymbols. N1 may be equal to or different from M. The V2X transmission UEmay transmit sidelink control information (SCI) including time/frequencyallocation information of the PSSCH through the PSCCH. The V2X receptionUE may receive and decode the PSCCH, and then may acquire thetime/frequency allocation information of the PSSCH and decode the PSSCH.FIG. 10 illustrates the PSSCH constituted by (M−N2) frequency blocks,which is physically continuously positioned after the PSCCH constitutedby the N1 frequency blocks, although they may not be physicallycontinuously positioned (that is, the PSSCH may be logicallycontinuously positioned without being physically continuously positionedafter the PSCCH). In addition, although not shown in FIG. 10, a PSFCHmay exist in the later part of the K symbols. More specifically, thePSCCH and the PSSCH may be constituted by the K1 symbols and a guardsymbol, and the PSFCH may be constituted by the K2 symbols, and K1+ thenumber of guard symbols+K2 may be equal to or smaller than K. The guardsymbol may be one or at least two OFDM symbols. The V2X reception UE maydecode the PSSCH, and then transmit the PSFCH including the result (thatis, ACK/NACK information) to the V2X transmission UE.

At the i-th transmission time, the V2X UE using a sidelink resourcestructure of FIG. 10 may determine each of transmission power(P_(PSSCH)) of the PSCCH and transmission power (P_(PSSCH)) of the PSSCHthrough Equation 5.

P _(PSSCH)(i)=γ1+min{Pcmax(i),P _(0_PSCCH)+α_(PSCCH)*PL(q)+β+Δ_(PSSCH)(i)}[dBm]

P _(PSSCH)(i)=γ2+min{Pcmax(i),P _(0_PSSCH)+α_(PSSCH)*PL(q)+β+Δ_(PSSCH)(i)}[dBm]  Equation 5

In Equation 5, each parameter indicates the following.

-   -   γ1, γ2: Referring to FIG. 10, since the PSCCH and the PSSCH are        frequency-division-multiplexed, the PSCCH and the PSSCH may be        simultaneously transmitted at the i-th time. Therefore, the        transmission power of the V2X UE is required to be properly        distributed to the PSCCH and the PSSCH at the i-th sidelink        transmission time. γ1 and γ2 indicate values which distribute        the power that the PSCCH and the PSSCH use and may be expressed        as shown in Equation 6.

γ1=10 log 10{(10{circumflex over ( )}(ε/10)×N1)/[(M−N1)+10{circumflexover ( )}(ε/10)×N1]}[dB]

γ2=10 log 10{[10{circumflex over( )}(ε/10)×(M−N1)]/[(M−N1)+10{circumflex over ( )}(ε/10)×N1]}[dB]  Equation 6

ε indicates a value representing a difference between PSDs of the PSCCHand the PSSCH, and may have a unit of [dB]. For example, when the PSCCHand the PSSCH use the same PSD, ε may be 0. Generally, a control channelis required to guarantee the reliability higher than that of a datachannel. In that case, the PSCCH has the higher PSD than that of thePSSCH. For example, when ε=3, it may indicate that the PSCCH has the PSDhigher than that of the PSSCH by 3 dB. The fixed value is always used asthe value of ε (for example, ε=3) or the base station may transmit thevalue of ε to the UE through system information or RRC configuration. Inthat case, as illustrated in FIGS. 8 and 9, different values of ε may beset for each resource pool.

-   -   In Equation 5, β may indicate 10 log 10[(M−N1)+10{circumflex        over ( )}(ε/10)×N1] [dB].    -   In Equation 5, a definition and a method of use of parameters        other than γ1, γ2, and β may be the same as what illustrated in        FIGS. 8 and 9. For example, with respect to the transmission        power parameters used in Equation 5, the transmission UE may use        the value set by the base station or use the value preset to the        UE, by means of the methods mentioned in FIGS. 8 to 10. For        example, UEs existing out of the coverage of the base station        may not receive sidelink transmission power parameters set by        the base station. Therefore, these UEs may use values preset        with respect to the parameters. The set values may include 0, 0        dB, or 0 dBm. The preset value may indicate a value input in a        UE at the factory or, when the UE has existed within the        coverage of the base station (the UE is positioned out of the        coverage of the base station now), may indicate a value set by        the base station.

In another example, even though UEs exist within the coverage of thebase station, exchange of parameters between the UEs, which are toperform unicast/groupcast communication, may not be performed when anunicast UE pair for performing unicast communication is not formed (forexample, a case in which PC5 RRC configuration is not completed), orbefore a UE grouping for performing groupcast communication is formed.Therefore, the transmission UE for unicast and groupcast communicationsmay not set a sidelink transmission power value based on a sidelink pathloss value. To this end, with respect to the mentioned parameters, apreset value may be used, or a value transmitted from the base stationthrough RRC configuration and system information of the base station maybe used. The values of the parameters used at this time may be differentfrom the values of the parameters used after PC5 RRC configuration.PL(q) that the transmission UE uses before PC5 RRC configuration inEquation 7, Equation 8, Equation 9, Equation 10, and Equation 11 mayindicate a path loss value with respect to Uu link between the basestation and the transmission UE, not the sidelink path loss value. Inaddition, when the UE uses the preset parameters, each of the parametersmay include the value of 0, 0 dB, or 0 dBm.

In another example, the preset transmission power values or thetransmission power values set by the base station, of the PSCCH, thePSSCH, and the PSFCH may be expressed as the transmission power valueand the offset value with respect to one channel. For example, when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH arepreset, the transmission power value of the PSCCH may be set to be [X]dBm, and the offset value for transmission power of the PSSCH and thePSFCH may be set to be +/−[Y] dB (or dBm), based on the transmissionpower value of the PSCCH. It may be equally applied even when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH are setby the base station.

FIG. 11 illustrates a V2X frame structure according to an embodiment ofthe disclosure.

Referring to FIG. 11, which is considered to be a combination of FIGS. 9and 10, it illustrates that a PSCCH and a PSSCH arefrequency-division-multiplexed in K1 symbols, and in remaining K2symbols, only the PSSCH is transmitted without PSCCH transmission. ThePSCCH may be constituted by N1 frequency blocks on the frequency axis,and may be constituted by K1 symbols on the time axis. The PSSCH may beconstituted by N2 frequency blocks during the length of the K1 symbols,and may be frequency-divided with the PSCCH. The PSSCH are notfrequency-divided with the PSCCH during the length of the K2 symbols,and may be constituted by M frequency blocks. The sum of N1 and N2 maybe equal to or different from M. FIG. 11 illustrates that the PSCCHconstituted by the N1 frequency blocks and the PSSCH constituted by(M−N2) frequency blocks are physically continuously positioned, but theymay not be physically continuously positioned (that is, they may belogically continuously positioned without being physically continuouslypositioned). Meanwhile, the values of K1 and K2 may be equal to ordifferent from each other, and when the values of K1 and K2 aredifferent from each other, it may be K1>K2 or K1<K2. The V2Xtransmission UE may transmit sidelink control information includingtime/frequency allocation information of the PSSCH through the PSCCH.The V2X reception UE may receive and decode the PSCCH, and then mayacquire the time/frequency allocation information of the PSSCH anddecode the PSSCH. FIG. 11 illustrates the PSSCH constituted by the K2symbols, which is physically continuously positioned after the PSCCHconstituted by the K1 symbols, although they may not be physicallycontinuously positioned (that is, the PSSCH may be logicallycontinuously positioned without being physically continuously positionedafter the PSCCH).

Although not shown in FIG. 11, a PSFCH may exist within a sidelinkresource constituted by K symbols. The PSCCH may be constituted by theK1 symbols, the PSSCH may be constituted by the K1+K2 symbols and aguard symbol, and the PSFCH may be constituted by K3 symbols, and K1+K2+the number of guard symbols+K3 may be equal to or smaller than K. Theguard symbol may be one or at least two OFDM symbols. In addition, onthe frequency axis of the PSFCH, the size of resource blocks may beequal to or different from the size of resource blocks of the PSCCH andthe PSSCH. The V2X reception UE may decode the PSSCH, and then transmitthe PSFCH including the result (that is, ACK/NACK information) to theV2X transmission UE.

At the i-th transmission time, the V2X UE using a sidelink resourcestructure of FIG. 11 may determine transmission power (P_(PSSCH)) of thePSCCH and transmission power (P_(PSSCH)) of the PSSCH by using one ofmethods mentioned below.

Method 1) Parameters for determining P_(PSCCH) and P_(PSSCH) areindependently set.

Method 1-1) Scalding Down or Scaling Up of Transmission Power

-   -   A UE may temporarily calculate values of P_(PSCCH) and P_(PSSCH)        through Equation 7.

P _(PSSCH)(i)=P _(0_PSCCH)+α_(PSCCH) *PL(q)+10 log10(N1*2^(μ))+Δ_(PSSCH)(i)[dBm]

P _(PSSCH-1)(i)=P _(0_PSSCH)+α_(PSSCH) *PL(q)+10 log10(N2*2^(μ))+Δ_(PSSCH)(i)[dBm]

P _(PSSCH-2)(i)=P _(0_PSSCH)+α_(PSSCH) *PL(q)+10 log10(M*2^(μ))+Δ_(PSSCH)(i)[dBm]  Equation 7

In Equation 7, referring to FIG. 11, P_(PSSCH-1) may indicatetransmission power of the PSSCH during a section of K1 symbols when thePSCCH and the PSSCH are frequency-divided and transmitted. Referring toFIG. 11, P_(PSSCH-2) may indicate transmission power of the PSSCH duringa section of K2 symbols when only the PSCCH is transmitted. Within onesidelink transmission time (for example, sidelink transmission time i),when transmission power of symbols of the same channel is changed, aproblem may occur. Specifically, in FIG. 11, the PSCCH and the PSSCH aresimultaneously transmitted during the section of K1 symbols, and onlythe PSSCH is transmitted during the section of K2 symbols. Asillustrated in Equation 7, the PSCCH and the PSSCH may use differenttransmission power control parameters. Therefore, at the sidelinktransmission time i, the transmission power for transmitting the K1symbols may be different from the transmission power for transmittingthe K2 symbols. In that case, due to the phase shift and discontinuity,a transmission signal may be transmitted while being distorted. In orderto solve this problem, it is required to set the transmission power usedfor transmitting the K1 symbols and the transmission power used fortransmitting the K2 symbols to have the same value, and it may beachieved through Equation 8 or Equation 9.

P _(Sidelink)(i)=min{Pcmax(i),P _(PSCCH)(i)+P _(PSSCH-1)(1),P_(PSSCH-2)(i)}   Equation 8

P _(Sidelink)(i)=min{Pcmax(i),max[P _(PSSCH)(i)+P _(PSSCH-1)(i),P_(PSSCH-2)(i)]}  Equation 9

In Equation 8 and Equation 9, each parameter may indicate the following.

-   -   P_(Sidelink)(i): Sidelink transmission power at the i-th        sidelink transmission time    -   Pcmax(i): Pcmax(i) is equal to what described in Equation 1,        Equation 3, Equation 4, Equation 5, and Equation 6.    -   P_(PSSCH)(i): PSCCH transmission power at the i-th sidelink        transmission time    -   P_(PSSCH-1)(i): PSSCH transmission power in symbols during which        the PSCCH and the PSSCH are frequency-divided and transmitted at        the i-th sidelink transmission time    -   At the i-th sidelink transmission time, a case of        P_(PSSCH)(i)+P_(PSSCH-1)(i)<P_(PSSCH-2)(i)<Pcmax(i) may occur.    -   Transmission power used for the i-th sidelink transmission may        be P_(Sidelink)(i)=P_(PSSCH)(i)+P_(PSSCH-1)(i) by Equation 8,        and may scale down P_(PSSCH-2)(i) obtained by Equation 7 by w1        such that P_(PSSCH)(i)+P_(PSSCH-1)(i)=w1*P_(PSSCH-2)(i) is        satisfied. w1 may have a value which is larger than 0 and equal        to 1, or smaller than 1.    -   In a case of using Equation 9, transmission power used for the        i-th sidelink transmission may be        P_(Sidelink)(i)=P_(PSSCH-2)(i), and may scale up        P_(PSCCH)(i)+P_(PSSCH-1)(i) obtained by Equation 7 by w1 such        that P_(PSSCH-2)(i)=w1 [P_(PSSCH)(i)+P_(PSSCH-1)(i)] is        satisfied. w1 may have a value larger than 1.    -   In another example, at the i-th sidelink transmission time, a        case of P_(PSSCH-2)(i)<P_(PSSCH)(i)+P_(PSSCH-1)(i)<Pcmax(i) may        occur.    -   Transmission power used for the i-th sidelink transmission may        be P_(Sidelink)(i)=P_(PSSCH-2)(i) by Equation 8, and may scale        down P_(PSSCH)(i)+P_(PSSCH-1)(i) obtained by Equation 7 by w1        such that P_(PSSCH-2)(i)=w1 [P_(PSSCH)(i)+P_(PSSCH-1)(i)] is        satisfied. w1 may have a value which is larger than 0 and equal        to 1, or smaller than 1.    -   Transmission power used for the i-th sidelink transmission may        be P_(Sidelink)(i)=P_(PSCCH)(i)+P_(PSSCH)-1(1) by Equation 9,        and may scale up P_(PSSCH-2)(i) obtained by Equation 7 by w1        such that P_(PSSCH)(i)+P_(PSSCH-1)(i)=w1*P_(PSSCH-2)(i) is        satisfied. w1 may have a value larger than 1.

Method 1-2) Sidelink transmission power is determined by thetransmission power of the K1 symbols.

-   -   Method 1-2 is the same as method 1-1 in that the UE temporarily        calculates values of P_(PSCCH) and P_(PSSCH-1) through        Equation 7. However, unlike method 1-1, in method 1-2,        P_(PSSCH)-2 mentioned in Equation 7 may not be calculated.        Therefore, transmission power at the i-th sidelink transmission        time may be determined as shown in Equation 10.

P _(Sidelink)(i)=min{Pcmax(i),P _(PSCCH)(i)+P _(PSSCH-1)(i)}  Equation10

When sizes of frequency blocks in the K1 symbols and the K2 symbols aredifferent, or since values of transmission power control parameters aredifferent, transmission power values of the K1 symbols and the K2symbols are different, as previously illustrated, P_(PSSCH-2)(i) may bescaled up or scaled down.

Method 1-3) Sidelink Transmission Power is Determined by theTransmission Power of the K2 Symbols.

-   -   In method 1-3, transmission power at the i-th sidelink        transmission time may be determined by Equation 11.

P _(Sidelink)(i)=min{Pcmax(i),P _(PSSCH)-20}  Equation 11

In Equation 11, P_(PSSCH-2)(i) may be equal to P_(PSSCH-2)(i)illustrated in Equation 7. The UE may use P_(PSSCH-2)(i) obtained byEquation 11 to calculate transmission powers of the PSCCH and PSSCHtransmitted in the section of K1 symbols. More specifically, throughP_(PSSCH-2)(i) obtained by Equation 11, and P_(PSSCH)(i) andP_(PSSCH-1)(i) illustrated in Equation 7, temporary transmission powersof the PSCCH and the PSSCH in the section of K1 symbols may becalculated and values of X1, X2, and Y may be calculated as shown inEquation 12.

X1=10{circumflex over ( )}[P _(PSSCH)(i)/10],X2=10{circumflex over( )}[P _(PSSCH-1)(i)/10],Y=10{circumflex over ( )}[P_(Sidelink)(i)/10]   Equation 12

The UE may determine transmission powers of the PSCCH and the PSSCHtransmitted in the section of K1 symbols through Equation 13, by usingthe values of X1, X2, and Y obtained by Equation 12.

P _(PSCCH)(i)=10 log 10[X1*Y/(X1+X2)]

P _(PSSCH-1)(i)=10 log 10[X2*Y/(X1+X2)]  Equation 13

Method 2) Parameters for determining P_(PSCCH) and P_(PSSCH) are set tobe the same.

In a case of method 2, since parameters for determining transmissionpowers of the PSCCH and the PSSCH are set to be the same, the parametersof the PSCCH and the PSSCH, which are illustrated in Equation 3,Equation 4, Equation 5, and Equation 7, may be the same. Morespecifically, at the i-th sidelink transmission time, it may beindicated that P_(0_PSCCH)=P_(0_PSSCH)=P₀, α_(PSCCH)=α_(PSSCH)=α, andΔ_(PSCCH)=Δ_(PSSCH)=Δ. Another precondition of method 2 is thatP_(PSCCH) and P_(PSSCH) may have the fixed power density offset or theset power density offset. Under these assumptions, method 2 may have twomethods described below.

Method 2-1) Sidelink Transmission Power is Determined by theTransmission Power of the K1 Symbols.

At the section of the K1 symbols during which the PSCCH and the PSSCHare frequency-divided and transmitted at the i-th sidelink transmissiontime, P_(PSCCH) and P_(PSSCH-1) may be determined by Equation 14.

P _(PSCCH)(i)=γ1+P ₀ +αPL(q)+β+Δ(i)[dBm]

P _(PSSCH-1)(i)=γ2+P ₀ +αPL(q)+β+Δ(i)[dBm]  Equation 14

In Equation 14, γ1 and γ2 may be equal to what defined in Equation 6. InEquation 14, 13 may indicate 10 log 10[(M−N1)+10{circumflex over( )}(ε/10)×N1] [dB]. Transmission power at the i-th sidelinktransmission time may be calculated as shown in Equation 10, by usingEquation 14. In method 2-1, when sizes of frequency blocks in the K1symbols and the K2 symbols are different, the value ofP_(PSSCH)(i)+P_(PSSCH-1)(i) may be different from P_(PSSCH-2)(i). Inthat case, as illustrated above, P_(PSSCH-2)(i) may be scaled up orscaled down.

Method 2-2) Sidelink transmission power is determined by thetransmission power of the K2 symbols.

Unlike method 2-1, at the section of K2 symbols during which the PSCCHand the PSSCH are not frequency-divided at the i-th sidelinktransmission time, sidelink transmission power may be determined byEquation 11. P_(Sidelink)(i) having been determined by Equation 11 maybe distributed by Equation 12 and Equation 13. Meanwhile, with respectto the transmission power parameters used in Equation 7, Equation 8,Equation 9, Equation 10, and Equation 11, the transmission UE may usethe value set by the base station or use the value preset to the UE, bymeans of the methods mentioned in FIGS. 8 to 11. For example, UEsexisting out of the coverage of the base station may not receive settingwith respect to transmission power parameters from the base station.Therefore, these UEs may use values preset with respect to theparameters. The set values may include 0, 0 dB, or 0 dBm. The presetvalue may indicate a value input in a UE at the factory or, when the UEhas existed within the coverage of the base station (the UE ispositioned out of the coverage of the base station now), may indicate avalue set by the base station. In another example, even though UEs existwithin the coverage of the base station, exchange of parameters betweenthe UEs, which are to perform unicast/groupcast communication, may notbe performed when an unicast UE pair for performing unicastcommunication is not formed (for example, a case in which PC5 RRCconfiguration is not completed), or before a UE grouping for performinggroupcast communication is formed. Therefore, the transmission UE forunicast and groupcast communications may not set a transmission powervalue. To this end, with respect to the mentioned parameters, a presetvalue may be used, or a value transmitted from the base station throughRRC configuration and system information of the base station may beused. The values of the parameters used at this time may be differentfrom the values of the parameters used after PC5 RRC configuration.PL(q) that the transmission UE uses before PC5 RRC configuration inEquation 7, Equation 8, Equation 9, Equation 10, and Equation 11 mayindicate a path loss value with respect to Uu link between the basestation and the transmission UE, not the sidelink path loss value. Inaddition, when the UE uses the preset parameters, each of the parametersmay include the value of 0, 0 dB, or 0 dBm. In another example, thepreset transmission power values or the transmission power values set bythe base station, of the PSCCH, the PSSCH, and the PSFCH may beexpressed as the transmission power value and the offset value withrespect to one channel. For example, when the transmission power valuesof the PSCCH, the PSSCH, and the PSFCH are preset, the transmissionpower value of the PSCCH may be set to be [X] dBm, and the offset valuefor transmission power of the PSSCH and the PSFCH may be set to be+/−[Y] dB (or dBm), based on the transmission power value of the PSCCH.It may be equally applied even when the transmission power values of thePSCCH, the PSSCH, and the PSFCH are set by the base station.

FIG. 12 illustrates a V2X frame structure according to an embodiment ofthe disclosure.

Referring to FIG. 12, similar to FIGS. 8 and 9, it illustrates that aPSCCH and a PSSCH are time-division-multiplexed, but unlike FIG. 8,illustrates that the PSCCH and the PSSCH are constituted by differentnumbers of resource blocks on the frequency axis. That is, on thefrequency axis, the PSCCH may be constituted by M frequency blocks, andthe PSSCH may be constituted by N1 frequency blocks (M>N1). Meanwhile,similar to FIGS. 8 and 9, on the time axis, the PSCCH may be constitutedby K1 symbols, and the PSSCH may be constituted by K2 symbols. Thevalues of K1 and K2 are equal to or different from each other. Inaddition, when the values of K1 and K2 are different from each other,the values may be K1>K2 or K1<K2. The V2X transmission UE may transmitsidelink control information (SCI) including time/frequency allocationinformation of the PSSCH through the PSCCH. The V2X reception UE mayreceive and decode the PSCCH, and then may acquire the time/frequencyallocation information of the PSSCH and decode the PSSCH. FIG. 12illustrates the PSSCH constituted by the K2 symbols, which is physicallycontinuously positioned after the PSCCH constituted by the K1 symbols,although they may not be physically continuously positioned (that is,the PSSCH may be logically continuously positioned without beingphysically continuously positioned after the PSCCH). In addition,although not shown in FIG. 12, a PSFCH may exist within a sidelinkresource constituted by K symbols. The PSCCH may be constituted by theK1 symbols, the PSSCH may be constituted by the K2 symbols and a guardsymbol, and the PSFCH may be constituted by K3 symbols, and K1+K2+ thenumber of guard symbols+K3 may be equal to or smaller than K. The guardsymbol may be one or at least two OFDM symbols. In addition, on thefrequency axis of the PSFCH, the size of resource blocks may be equal toor different from the size of resource blocks of the PSCCH and thePSSCH. The V2X reception UE may decode the PSSCH, and then transmit thePSFCH including the result (that is, ACK/NACK information) to the V2Xtransmission UE.

At the i-th transmission time, the V2X UE using a sidelink resourcestructure of FIG. 10 may determine each of transmission power(P_(PSSCH)) of the PSCCH and transmission power (P_(PSSCH)) of the PSSCHthrough Equation 15.

P _(PSSCH)(i)=min{Pcmax(i),P _(0_PSCCH)+α_(PSCCH) *PL(q)+10 log10(M*2^(μ))+Δ_(PSSCH)(i)}[dBm]

P _(PSSCH)(i)=min{Pcmax(i),P _(0_PSSCH)+α_(PSSCH) *PL(q)+10 log10(N1*2^(μ))+Δ_(PSSCH)(i)}[dBm]  Equation 15

In Equation 15, each parameter may be interpreted to be the same asEquation 4 illustrated in FIG. 9.

In addition, with respect to the transmission power parameters used inEquation 15, the transmission UE may use the value set by the basestation or use the value preset to the UE, by means of the methodsmentioned in FIGS. 8 to 12. For example, UEs existing out of thecoverage of the base station may not receive transmission powerparameters set by the base station. Therefore, these UEs may use valuespreset with respect to the parameters. The set values may include 0, 0dB, or 0 dBm. The preset value may indicate a value input in a UE at thefactory or, when the UE has existed within the coverage of the basestation (the UE is positioned out of the coverage of the base stationnow), may indicate a value set by the base station.

In another example, even though UEs exist within the coverage of thebase station, exchange of parameters between UEs, which are to performunicast/groupcast communication, may not be performed when a UE pairingfor performing unicast communication is not formed (for example, beforePC5 RRC configuration is completed), or before a UE grouping forperforming groupcast communication is formed. A transmission UE for theunicast and groupcast communications may not set a sidelink transmissionpower value, based on sidelink path loss estimation. To this end, withrespect to the mentioned parameters, the UE may use the preset value orthe value transmitted from the base station through RRC configurationand system information of the base station. The values of the parametersused at this time may be different from the values of the parametersused after PC5 RRC configuration. PL(q) that the transmission UE usesbefore PC5 RRC configuration in Equation 7, Equation 8, Equation 9,Equation 10, and Equation 11 may indicate a path loss value with respectto Uu link between the base station and the transmission UE, not thesidelink path loss value. In addition, when the UE uses the presetparameters, each of the parameters may include the value of 0, 0 dB, or0 dBm.

In another example, the preset transmission power values or thetransmission power values set by the base station, of the PSCCH, thePSSCH, and the PSFCH may be expressed as the transmission power valueand the offset value with respect to one channel. For example, when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH arepreset, the transmission power value of the PSCCH may be set to be [X]dBm, and the offset value for transmission power of the PSSCH and thePSFCH may be set to be +/−[Y] dB (or dBm), based on the transmissionpower value of the PSCCH. It may equally applied even when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH are setby the base station.

FIG. 13 illustrates a multiplexing method of a sidelink channel within asidelink resource according to an embodiment of the disclosure.

Referring to FIG. 13, as shown in FIG. 11, it illustrates that a PSCCHand a PSSCH are frequency-division-multiplexed in K1 symbols, and onlythe PSSCH is transmitted in K2 symbols, but unlike FIG. 11, illustratesthat a PSFCH constituted by K3 symbols exists. The value of K3 may be 1or an integer larger than 1 (for example, 2 or 3). That is, the Ksymbols may be constituted by K1 PSCCH/PSSCH symbolsfrequency-division-multiplexed, K2 PSSCH symbols, K3 PSFCH symbols, andguard symbols (GAP symbols). The values of K1 and K2 may be equal to ordifferent from each other. In addition, when the values of K1 and K2 aredifferent from each other, the values may be to be K1>K2 or K1<K2. Thevalue may be K1+K2+ the number of guard symbols 1+K3+ the number ofguard symbols 2 may be equal to or smaller than K, and the guard symbol1 and the guard symbol 2 may one or at least two OFDM symbols. The guardsymbol 1 and the guard symbol 2 may be OFDM symbols having differentlengths. For example, the guard symbol 1 may be constituted by two OFDMsymbols, and the guard symbol 2 may be constituted by one OFDM symbol.In addition, in FIG. 13, M is illustrated as the size of resource blockson the frequency axis of the PSFCH, but the size of resource blocks ofthe PSFCH may be equal to or different from the size of resource blocksof the PSCCH and the PSSCH. The V2X reception UE may decode the PSSCH,and then transmit the PSFCH including the result (that is, ACK/NACKinformation) to the V2X transmission UE.

Referring to FIG. 13, the V2X transmission UE may transmit sidelinkcontrol information (SCI) through the PSCCH constituted by K1 symbols onthe time axis and N2 frequency blocks on the frequency axis. Thesidelink control information may include time/frequency allocationinformation of the PSSCH constituted by K1+K2 symbols on the time axisand M frequency blocks on the frequency axis and be then transmitted.The V2X reception UE may receive, from the transmission UE, and decodethe PSCCH, and may then acquire the time/frequency allocationinformation of the PSSCH and decode the PSSCH. FIG. 13 illustrates thePSSCH constituted by the K2 symbols, which is physically continuouslypositioned after the PSCCH constituted by the K1 symbols, although theymay not be physically continuously positioned (that is, the PSSCH may belogically continuously positioned without being physically continuouslypositioned after the PSCCH).

Meanwhile, as shown in FIG. 11, in FIG. 13, the PSCCH may be constitutedby N1 frequency blocks on the frequency axis. The PSSCH may beconstituted by the N2 frequency blocks during the length of the K1symbols, and may be constituted by M frequency blocks during the lengthof the K2 symbols (N1+N2=M). At the i-th transmission time, the V2Xtransmission UE using a sidelink resource structure of FIG. 13 maydetermine transmission power (P_(PSSCH)) of the PSCCH and transmissionpower (P_(PSSCH)) of the PSSCH through Equation 16, Equation 17 orEquation 18.

P _(PSCCH)(i)=X1+min{Pcmax(i),10 log 10(X2*2^(μ))+P _(0_PSCCH)+α_(PSCCH)*PL(q)}[dBm]  Equation 16

P _(PSSCH)(i)=X1+min{Pcmax(i),10 log 10(X2*2^(μ) +P _(0_PSCCH)+α_(PSCCH)*PL(q),P _(congestion)}[dBm]  Equation 17

P _(PSSCH)(i)=X1+min{Pcmax(i),10 log 10(X2*2^(μ))+P _(0_PSCCH)+α_(PSCCH)*PL(q),P _(congestion) ,P _(Range)}[dBm]  Equation 18

Each parameter of Equation 16, Equation 17, and Equation 18 may indicatethe following.

-   -   Pcmax(i): Pcmax(i) indicates the maximum UE transmission output        at the i-th sidelink transmission and a P-max value (when there        is no base station, a preset value) set by a base station        through system information or RRC, and may be determined by a UE        by means of UE power class included in the UE.    -   P_(0_PSCCH): P_(0_PSCCH) may indicate a value (when there is no        base station, a preset value) set by a base station through        system information or RRC in order to guarantee link quality of        a reception UE.    -   α_(PSCCH): α_(PSCCH) is a parameter for compensating a path loss        value and has a value between 0 and 1, and may indicate a value        (when there is no base station, a preset value) set by a base        station through system information or RRC. For example, when        α_(PSCCH)=1, 100% of path loss may be compensated, and when        α_(PSCCH)=0.8, only 80% of path loss may be compensated.

10 log₁₀(10ε/10×M _(PSCCH) /M _(PSSCH)+10ε/10×M _(PSCCH))

-   -   X1: X1 indicates and M_(PSCCH) and M_(PSSCH) may indicate the        sizes of frequency blocks allocated for transmitting the PSCCH        and the PSSCH, respectively. In addition, ε is a parameter for        power boosting of the PSCCH. For example, when the PSCCH        performs power boosting in order to maintain a PSD higher 3 dB        than that of the PSSCH, ε may be 3. When the PSCCH and the PSSCH        maintain the same PSD (or a case in which power boosting is not        performed), ε may be 0. The fixed value may be used as the value        of ε (that is, ε is fixed to 3), or the value of ε may be set        through RRC and system information of the base station. When        there is no base station, the value of ε may be preset. For        example, in a case in which the value of ε is set, the V2X        transmission UE and reception UE may receive the value of ε        which is set through PC-5 RRC, when unicast connection is        configured.    -   X2: X2 indicates 10 log₁₀(M_(PSSCH)10ε/10×M_(PSCCH)), and        M_(PSSCH), M_(PSSCH), and ε may be the same as the description        of X1 above.

2μ: 2μ may be a parameter for compensating a power spectral density(PSD) which varies depending on a subcarrier spacing. For example, acase of using a subcarrier spacing of 15 kHz may indicate that μ=0. Evenif the same number of frequency blocks are used, when the subcarrierspacing is doubled to 30 kHz, the PSD may be reduced by half comparedwith the case of using the subcarrier spacing of 15 kHz. Therefore, inorder to compensate the PSD, power is required to be doubled. Morespecifically, for example, when two frequency blocks are used, 10 log10(2×20)=3 dB is required for the subcarrier spacing of 15 kHz, whereas,in order to maintain the same PSD as that for the subcarrier spacing of15 kHz, transmission power is required to be increased to 10 log10(2×21)=6 dB for the subcarrier spacing of 30 kHz.

PL: PL may indicate an estimated path loss value. The path loss valuemay be estimated by Equation 2.

P_(Congestion): P_(Congestion) included in Equation 17 and Equation 18is a parameter reflecting a congestion level of the V2X transmission UE,and may indicate the maximum transmission power that the V2Xtransmission UE may use according to the congestion level. Morespecifically, when the base station determines that the congestion levelis high in a resource pool configured thereby, the base station maytransmit a value of P_(Congestion) to the V2X transmission UE throughsystem information and RRC configuration. In another example, the V2Xtransmission UE may receive a set value of P_(Congestion) when unicastlink connection is configured through PC-5 RRC. In another example, theV2X transmission UE may use a value of P_(Congestion) included inpreconfigured resource pool information. The value of P_(Congestion) hasa unit of [dBm] and may have a range from −41 [dBm] to 31 [dBm] by 1[dBm]. The value of P_(Congestion) may be associated with the priorityof the PSSCH that the V2X transmission UE transmits. That is, when thepriority of the PSSCH that the V2X transmission UE transmits is high,even though the congestion level is high, the set value ofP_(Congestion) may be high (for example, 31 [dBm]) because thetransmission of the PSCCH and the PSSCH corresponding thereto should besuccessfully performed. On the other hand, when the priority of thePSSCH that the V2X transmission UE transmits is low and the congestionlevel is high, since failure in transmission of the PSCCH and the PSSCHcorresponding thereto makes no problem (or the transmission may be givenup), the set value of P_(Congestion) may be low (for example, −41[dBm]). Meanwhile, the value of P_(Congestion) may include the value of−∞. Since the value indicates −∞ in a unit of dBm, when the value isconverted to a linear domain, the value may 10{circumflex over( )}(−∞/10)=10{circumflex over ( )}(−∞)=1/(10{circumflex over ( )}∞)≈0[mW]. In Equation 17, when P_(Congestion)=−∞, the value may indicateP_(PSCCH)(i)=X1+P_(Congestion)=P_(Congestion)=−∞ [dBm]. As mentionedabove, it may indicate that in the linear domain, the transmission powerof the PSCCH is 0 [mW] (that is, the PSCCH is not transmitted).

The resource pool information of the PSCCH may be configured from thebase station or PC-5 RRC, or may be preconfigured. Within the configured(or preconfigured) resource pool, a V2X resource allocation mode, inwhich the V2X transmission UE selects a resource for transmitting thePSCCH through a sensing process, may exist. The sensing process mayindicate a process of decoding sidelink control information (SCI)transmitted through the PSCCH and a process of measuring RSRP of theDMRS of the PSSCH associated with the PSCCH. A mode in which the V2Xtransmission UE selects a resource through the sensing process may becalled mode-2. V2X transmission UEs operating in mode-2 may performdecoding of the PSCCH to select the PSCCH resource which may be occupiedthereby within the configured (or preconfigured) PSCCH resource pool orthe PSCCH resource region. In addition, the V2X transmission UE maymeasure the congestion level of the PSCCH transmitted from each slotwithin the PSCCH resource pool or the PSCCH resource region. Similarly,V2X transmission UEs operating in mode-2 may perform decoding of thePSCCH to select the PSSCH resource which may be occupied thereby withinthe configured (or preconfigured) PSSCH resource pool or the PSSCHresource region, and may measure RSRP of the DMRS transmitted throughthe PSSCH. In addition, the V2X transmission UE may measure thecongestion level of the PSSCH transmitted from each slot within thePSSCH resource pool or the PSSCH resource region.

In mode-2 mentioned above, the congestion level of the PSCCH or thePSSCH may be measured by means of a ratio (B/A) between the entirenumber of resources constituting the PSCCH resource pool (or PSCCHresource region) or the PSSCH resource pool (or PSSCH resource region)and the number of resources occupied by other UE. That is, when thecongestion level of the PSCCH is measured, A may be the entire number ofPSCCH resources constituting the PSCCH resource pool, and when thecongestion level of the PSSCH is measured, A may be the entire number ofPSSCH resources constituting the PSSCH resource pool. When thecongestion level of the PSCCH is measured, B may be calculated bycomparing the value of a received signal strength indicator (RSSI) ofthe PSCCH symbols with the critical value of the RSSI, which is set(oris preset) through the base station or PC-5 RRC. For example, assumingthat the PSCCH that each UE transmits within the PSCCH resource pool isconstituted by x symbols, the total received power (x total receivedpowers) for each of the symbols is obtained to obtain the average of xsymbols. Accordingly, the RSSI of the PSCCH that each UE transmits maybe measured. The V2X transmission UE may compare the measured value ofthe RSSI with the critical value of the RSSI, which is set (or preset)through the base station or PC-5 RRC, and may thus determine that thecorresponding PSCCH is occupied by other UE when the measured value ofthe RSSI is larger than the set critical value of the RSSI. Therefore,the corresponding PSCCH may be included in B. Meanwhile, when thecongestion level of the PSSCH is measured, B may be calculated bycomparing the value of the RSSI of the PSSCH symbols with the criticalvalue of the RSSI, which is set (or preset) through the base station orPC-5 RRC.

The measurement of the congestion level may be calculated during thespecific time section. For example, A and B may be measured with respectto the PSCCH resource (or PSSCH resource) existing within the timesection to [n-K, n-1] slot of the configured PSCCH resource pool (orPSSCH resource pool). Therefore, the congestion level measured in n slotmay indicate the congestion level measured with respect to the PSCCHresource (or PSSCH resource) existing within the time section to [n-K,n−1] slot. The fixed value (or preset value) may be used as K, or K maybe set through the base station or PC-5 RRC.

In Equation 17 and Equation 18, when the i-th PSCCH is transmitted, withrespect to the congestion level reflected in the value of P_(Congestion)which is set from the base station or PC-5 RRC, the congestionmeasurement time to obtain the congestion level is required to bedefined. For example, the base station or PC-5 RRC may use a measuredcongestion level result before k1 slot or k2 symbol prior to the i-thPSCCH transmission of the UE transmission UE. That is, the congestionlevel reflected in the value of P_(Congestion) used for the transmissionpower calculation of the PSCCH transmitted through the i-th slot mayindicate the congestion level measured at i-k1 slot or the congestionlevel measured before k2 symbol, based on the first symbol of the PSCCHtransmitted through the i-th slot. As mentioned above, the congestionlevel measured at i-k1 slot may indicate the congestion level measuredwith respect to the PSCCH resource existing within the [i-k1-K, i-k1-1]time section. In addition, the congestion level measured in i-k2 symbolmay indicate the congestion level measured with respect to the PSCCHresource existing within the [i-k2-K, i-k2-1] time section.

Equation 16 may be applied in a mode (mode-1) in which the base stationschedules a transmission resource of the V2X transmission UE by usingdownlink control information (DCI) transmitted through a PDCCH. Inanother example, when the value of P_(Congestion) of Equation 17 is notset from the base station or PC-5 RRC, Equation 16 may be applied, orwhen both the values of P_(Range) and P_(Congestion) of Equation 18 arenot set from the base station or PC-5 RRC, Equation 16 may be applied.

When the value of P_(Congestion) is set from the base station or PC-5RRC, Equation 17 may be applied. When both the values of P_(Range) andP_(Congestion) are set from the base station or PC-5 RRC, Equation 18may be applied. The value of P_(Congestion) may be omitted from Equation18. In that case, when the value of P_(Range) is set from the basestation or PC-5 RRC, Equation 18 may be applied.

P_(Range): P_(Range) of Equation 18 may indicate a transmission powervalue for meeting a range requirement in the V2X communication. Morespecifically, the range requirement or range information may indicatethe minimum distance which guarantees QoS (for example, delay time,reliability, data transmission rate, etc.) of a sidelink data packettransmitted through the unicast or groupcast communication. In theunicast or groupcast V2X communication, the transmission UE may receiveinformation on a range transferred from the upper layer (for example,application layer) thereof. The range information may be expressed as adistance having a unit of meter (m) or may be expressed as an index.That is, an application layer may provide the range information for anAS layer in units of meter (for example, 100 m). In another example, theapplication layer may provide a range index for the AS layer. In thiscase, the minimum distance may be mapped to each range index (that is,index 1=100 m, index 2=200 m, etc.). Upon receiving the rangeinformation, the AS layer may generate the value of P_(Range) mapped tothe corresponding range information. For example, the value of P_(Range)corresponding to the range of 100 m (or range index 1) and the value ofP_(Range) corresponding to the range of 200 m (or range index 2) may begenerated. In another example, upon receiving the range informationtransferred from the application layer, the AS layer may transfer thecorresponding information to RRC and generate the value of P_(Range) inRRC.

Meanwhile, referring to FIG. 3, the V2X UE may be configured withrespect to whether to perform sidelink transmission power by usingdownlink path loss with the base station or whether to perform sidelinktransmission power by using sidelink path loss between V2X UEs. Theinformation may be configured through the configuration of a path lossestimation signal that the V2X transmission UE or the V2X reception UEmay use. More specifically, as mentioned in FIG. 3, when sidelinktransmission power should be performed by using downlink path loss withthe base station, the V2X transmission UE and the V2X reception UE maybe configured by the base station such that path loss is estimated byusing a downlink synchronization signal block (SSB) or a CSI-RS (thatis, a SSB or a CSI-RS is configured as a path loss estimation signal).When sidelink transmission power is performed by using the sidelink pathloss between V2X UEs, the V2X transmission UE and the V2X reception UEmay be configured by the base station such that path loss is estimatedby using a sidelink reference signal (for example, a sidelink CSI-RStransmitted through the PSSCH or a DMRS transmitted through the PSSCH)(that is, a sidelink CSI-RS or a DMRS is configured as a path lossestimation signal).

The sidelink resource pool information may include information onwhether to apply the mentioned downlink path loss value to sidelinktransmission power, whether to apply an uplink path loss value tosidelink transmission power, or whether to use any path loss estimationsignal which may have the same meaning as it. For example, the basestation may transmit, to the UE, information on the sidelink resourcepool through system information or RRC configuration, and theinformation on the sidelink resource pool may include set parameters forsidelink transmission power, which may be used in the correspondingresource pool. The parameters for transmission power may include atleast one piece of information on P_(0_PSCCH), α_(PSCCH), and PL(q)mentioned in Equation 16, Equation 17, and Equation 18. Morespecifically, PL(0) may indicate the application of downlink path lossand may indicate to estimate downlink path loss by using the SSB (q=0).PL(1) may indicate the application of downlink path loss and mayindicate to estimate downlink path loss by using the downlink CSI-RS(q=1). In addition, PL(2) may indicate the application of sidelink pathloss and may indicate to estimate sidelink path loss by using thesidelink CSI-RS or the sidelink DMRS (q=2). In another example, it maybe explicitly written that the SSB, CSI-RS, sidelink CSI-RS, or sidelinkDMRS is used for the resource pool information through systeminformation or RRC configuration.

In another example, when there is no base station, the V2X transmissionUE may receive set parameters for sidelink transmission power from thepreconfigured resource pool information. In that case, the V2X UE mayacquire the transmission power parameters mentioned above from thepreconfigured resource pool information.

In another example, regardless of whether the base station exists, whenunicast connection with the V2X reception UE is configured, the V2Xtransmission UE may perform PC-5 RRC configuration. As parameters forsidelink transmission power are set from the PC-5 RRC (a case in whichthe sidelink resource pool information does not include the sidelinktransmission power parameters), or as information on the sidelinkresource pool is configured from the PC-5 RRC, the parameters forsidelink transmission power may be set (a case in which the sidelinkresource pool information includes the sidelink transmission powerparameters).

In Equation 16, Equation 17, and Equation 18, when downlink path loss isapplied or when sidelink path loss is applied, P_(0_PSCCH) and α_(PSCCH)may be set to have different values. That is, when the UE appliesdownlink path loss, P_(0_PSCCH) and α_(PSCCH) may be set to be A1 andB1, respectively, and when the UE applies sidelink path loss,P_(0_PSCCH) and α_(PSCCH) may be set to be A2 and B2, respectively. In ascenario where sidelink and Uu link (that is, downlink and uplink) sharea frequency, sidelink transmission power control may be performed withthe purpose of reducing interference caused by the sidelink transmissionin an uplink signal received by the base station, thus a downlink pathloss value may be applied. Unlike this, in a scenario where sidelink andUu link do not share a frequency, as sidelink quality is guaranteed andunnecessarily high transmission power is not used, a sidelink path lossvalue may be applied in order to reduce power consumption.

Meanwhile, unlike the examples mentioned above, the V2X UE may receiveall sidelink transmission power parameters when the downlink path lossvalue is applied and sidelink transmission power parameters when thesidelink path loss value is applied. That is, the V2X UE may receive,from the base station, through system information or RRC, or throughPC-5 RRC of the UE, all of: P_(0_PSSCH) and α_(PSCCH) which may be usedwhen the downlink path loss value is applied, and the type of path lossestimation signals for estimating downlink path loss (a SSB or adownlink CSI-RS); and P_(0_PSCCH) and α_(PSCCH) which may be used whenthe sidelink path loss value is applied, and the type of sidelink pathloss estimation signals for estimating sidelink path loss (a sidelinkCSI-RS or a sidelink DMRS).

As illustrated above, the resource pool information may include sidelinktransmission power parameter information including P_(0_PSCCH) andα_(PSCCH), and the type of path loss estimation signals for estimatingpath loss. More specifically, all of: P_(0_PSCCH_DL) and α_(PSCCH_DL)which may be used when the downlink path loss value is applied, and thetype of path loss estimation signals used for estimating downlink pathloss; and P_(0_PSSCH) SL and α_(PSSCH_SL) which may be used when thesidelink path loss value is applied, and the type of sidelink path lossestimation signals used for estimating sidelink path loss may beconfigured in the resource pool information (that is, both a SSB or adownlink CSI-RS and a sidelink CSI-RS or a sidelink DMRS areconfigured).

In another example, a path loss index set in the resource poolinformation may indicate the type of path loss estimation signals usedfor estimating path loss (for example, when q=0 indicates a SSB, q=1indicates a downlink CSI-RS, and q=2 indicates a sidelink CSI-RS or asidelink DMRS, both q=0 and q=2 or q=1 and q=2 are set).

When the V2X UE receives all of sidelink transmission power parameterswhen the downlink path loss value is applied and sidelink transmissionpower parameters when the sidelink path loss value is applied, the V2XUE may calculate the PSCCH transmission power through Equation 19 orEquation 20.

P _(PSCCH)(i)=X1+min{Pcmax(i),10 log 10(X2*2^(μ))+min{P1,P2}}[dBm]  Equation 19

P _(PSCCH)(i)=X1+min{Pcmax(i),min{P3,P4}}[dBm]  Equation 20

Each parameter of Equation 19 and Equation 20 may indicate thefollowing.

-   -   Pcmax(i), X1, X2, and 2^(μ) are the same as what described in        Equation 16.

P1: P1 indicates transmission power when the downlink path loss value isapplied, and may be P1=P_(0_PSCCH) DL+α_(PSCCH) DL*PL(q). The index qexpressing path loss may be omitted from P1.

P2: P2 indicates transmission power when the sidelink path loss value isapplied, and may be P2=P_(0_PSCCH_SL)+α_(PSCCH_SL)*PL(q). The index qexpressing path loss may be omitted from P2.

P3: P3 indicates transmission power when the downlink path loss value isapplied, and may be P3=P1+10 log 10(X2*2^(μ)). The index q expressingpath loss may be omitted from P3.

P4: P4 indicates transmission power when the sidelink path loss value isapplied, and may be P4=P2+10 log 10(X2*2^(μ)). The index q expressingpath loss may be omitted from P4.

Although not shown in Equation 19 and Equation 20, as shown in Equation17 and Equation 18, P_(Congestion) and P_(Range) may be included inEquation 19 and Equation 20. More specifically, Equation 19 may beexpressed as Equation 21.

P _(PSCCH)(i)=X1+min{Pcmax(i),P _(Congestion) ,P _(Range),10 log10(X2*2^(μ))+min{P1,P2}}[dBm]  Equation 21

Equation 21 illustrates a case in which both P_(Congestion) andP_(Range) are included, but one of P_(Congestion) and P_(Range) may beomitted from Equation 21.

Similarly, Equation 20 may be expressed as Equation 22.

P _(PSCCH)(i)=X1+min{Pcmax(i),P _(Congestion) ,P_(Range),min{P3,P4}}[dBm]   Equation 22

Equation 22 illustrates a case in which both P_(Congestion) andP_(Range) are included, but, as shown in Equation 21, one ofP_(Congestion) and P_(Range) may be omitted from Equation 22.

Equation 16, Equation 17, Equation 18, Equation 19, Equation 20,Equation 21, and Equation 22 are equations for determining thetransmission power value of the PSCCH. Similarly, the transmission powervalue of the PSSCH may be calculated, but the transmission power of thePSSCH may be calculated while being divided into two parts. The firstpart is transmission power of the PSSCH, which corresponds to K1 symbolsin FIG. 13, and may indicate PSSCH transmission power in symbols duringwhich the PSCCH and the PSSCH are frequency-division-multiplexed. It maybe defined as P_(PSSCH-1)(i). The second part is transmission power ofthe PSSCH, which corresponds to K2 symbols in FIG. 13, and may indicatePSSCH transmission power in symbols during which the PSCCH is notfrequency-division-multiplexed. It may be defined as P_(PSSCH-2)(i).P_(PSSCH-1)(i) may be defined by changing X1 defined in each of Equation16, Equation 17, Equation 18, Equation 19, Equation 20, Equation 21, andEquation 22 to X1-c. Referring to Equation 21 as an example, whenEquation 21 is used for the PSCCH transmission power, P_(PSSCH-1)(i) maybe calculated as shown in Equation 23.

P _(PSSCH-1)(i)=X1−ε+min{Pcmax(i),P _(Congestion) ,P _(Range),10 log10(X2*2^(μ))+min{P1,P2}}[dBm]  Equation 23

Parameters defined in Equation 23 may be the same as what described inEquation 21. When Equation 16, Equation 17, Equation 18, Equation 19,Equation 20, or Equation 22 is used to calculate the PSCCH transmissionpower value, X1 defined in each of the equations is changed to X1-c, andan equation for calculating P_(PSSCH-1)(i) may be thus derived. Inaddition, in order to calculate P_(PSSCH-1)(i) by means of themodification of Equation 23, Equation 22 may be used to applyP_(PSSCH-1)(i)=X1−ε+min{Pcmax(i), P_(Congestion), P_(Range), min{P3,P4}} [dBm].

The transmission power equation with respect to the first part of thePSCCH and the PSSCH constituting K1 symbols in FIG. 13 has beendescribed. Based on it, the equation for calculating the transmissionpower value (P_(PSSCH-2)(i)) with respect to the second part of thePSSCH may be defined by considering the following.

As illustrated in FIG. 13, when the number of symbols that a single V2Xtransmission UE uses for transmitting the i-th PSCCH and the PSSCH isK1+K2, each symbol constituting the K1+K2 symbols should have the sametransmission power. When the transmission power of each of the symbolsis not the same, since a guard section (or GAP) for power transient isrequired between symbols whose transmission power is changed,inefficient use of resources may occur. In addition, when thetransmission power level between symbols is changed, the receptionperformance of the corresponding symbols at the reception side may bedegraded due to the change in phase between the symbols. Therefore, thetransmission power of the K1 symbols during which the PSCCH and thePSSCH are frequency-division-multiplexed and the transmission power ofthe K2 symbols during which only the PSSCH is transmitted should beequally maintained. To this end, the transmission power value(P_(PSSCH-2)(i)) with respect to the second part of the PSSCH may bedetermined through Equation 24.

P _(PSCCH-2)(i)=P _(PSSCH)(i)+P _(PSSCH-1)(i)[dBm]  Equation 24

The parameters of Equation 24 are the same as what mentioned in Equation16, Equation 17, Equation 18, Equation 19, Equation 20, Equation 21,Equation 22, and Equation 23. In Equation 24, each of P_(PSSCH)(i) andP_(PSSCH-1)(i) may be smaller than the value of Pcmax(i) which is the UEmaximum transmission power (that is, P_(PSSCH)(i)<Pcmax(i) andP_(PSSCH-1)(i)<Pcmax(i)), but P_(PSSCH-2)(i) which is the sum ofP_(PSSCH)(i) and P_(PSSCH-1)(i) may be larger than Pcmax(i). In thatcase, P_(PSSCH-2)(i) may be recalculated through Equation 25 andEquation 26.

P _(PSSCH-2)(i)=min{Pcmax(i),P _(PSSCH-2)(i)}[dBm]  Equation 25

P _(PSSCH-2)(i)=δ·P _(PSSCH-2)(i)[dBm]  Equation 26

In Equation 26, δ is a scaling factor and may be larger than 0, andsmaller than or equal to 1. In order to satisfy P_(PSSCH-2)(i)<Pcmax(i),the value of δ may be set by the transmission UE.

In a case of P_(PSSCH-2)(i)=Pcmax(i) by Equation 25, as mentioned above,it occurs that P_(PSCCH)(i) P_(PSSCH-1)(i)=P_(PSSCH-2)(i)≥Pcmax(i). Thatis, since P_(PSSCH-2)(i) is limited by Pcmax(i) and the transmissionpower is thus changed, the transmission power ofP_(PSSCH)(i)+P_(PSSCH-1)(i) should be changed in order to enable the K1symbols and the K2 symbols to use the same transmission power. To thisend, β·[P_(PSSCH)(i)+P_(PSSCH-1)(i)] is used to scale down the sum ofthe transmission power such that P_(PSSCH)(i)+P_(PSSCH-1)(i)≤Pcmax(i) issatisfied. β is a scaling factor and may be larger than 0, and smallerthan or equal to 1. In another example, as described in Equation 12 andEquation 13, the transmission power of P_(PSSCH-2)(i) is redistributedat a rate between the transmission powers of P_(PSSCH)(i) andP_(PSSCH-1)(i) and may update each of the transmission power values ofP_(PSSCH)(i) and P_(PSSCH-1)(i). That is, when the updated transmissionpower values of P_(PSSCH)(i) and P_(PSSCH-1)(i) are defined asP_(PSSCH)(i) and P_(PSSCH-1)(i), respectively, they may be calculatedthrough P_(PSSCH)(i)=10 log 10[X1*Y/(X1+X2)] and P_(PSSCH-1)(i)=10 log10[X2*Y/(X1+X2)] (Equation 13). X1 and X2 are the same as what definedin Equation 12 and Y may indicate Y=10{circumflex over( )}[P_(PSSCH-2)(i)/10].

Similarly, when the transmission power of P_(PSSCH-2)(i) is changed tothat of P_(PSSCH-2)(i) by Equation 26, the transmission power ofP_(PSSCH)(i)+P_(PSSCH-1)(i) should be changed in order to enable the K1symbols and the K2 symbols to use the same transmission power. To thisend, as illustrated above, β·[P_(PSSCH)(i)+P_(PSSCH-1)(i)] is used toscale down the sum of the transmission power ofP_(PSSCH)(i)+P_(PSSCH-1)(i), or the changed transmission power value ofP_(PSSCH-2)(i) is redistributed at a ratio between the transmissionpowers of P_(PSSCH)(i) and P_(PSSCH-1)(i), and each of the transmissionpower values of P_(PSSCH)(i) and P_(PSSCH-1)(i) may thus be updated.

The transmission power parameters used in Equation 16, Equation 17,Equation 18, Equation 19, Equation 20, Equation 21, Equation 22,Equation 23, Equation 24, and Equation 26 may use the value set to thetransmission UE by the base station or may use the value preset in theUE by means of the methods mentioned in FIGS. 8 to 12. For example, UEsexisting out of the coverage of the base station may not receive settransmission power parameters from the base station. Therefore, theseUEs may use preset values with respect to the parameters. The set valuesmay include 0, 0 dB, or 0 dBm. The preset value may indicate a valueinput in the UE in the factory, or when the UE has existed within thecoverage of the base station (the UE is positioned out of the coverageof the base station now), may indicate a value set by the base station.

In another example, even though UEs exist within the coverage of thebase station, exchange of parameters between UEs, which are to performunicast/groupcast communication, may not be performed when a UE pairingfor performing unicast communication is not formed (for example, beforePC5 RRC configuration is completed), or before a UE grouping forperforming groupcast communication is formed. A transmission UE for theunicast and groupcast communications may not set a sidelink transmissionpower value, based on sidelink path loss estimation. To this end, withrespect to the mentioned parameters, the UE may use the preset value orthe value transmitted from the base station through RRC configurationand system information of the base station. The values of the parametersused at this time may be different from the values of the parametersused after PC5 RRC configuration. PL(q) that the transmission UE usesbefore PC5 RRC configuration may indicate a path loss value with respectto Uu link between the base station and the transmission UE, not thesidelink path loss value. In addition, when the UE uses the presetparameters, each of the parameters may include the value of 0, 0 dB, or0 dBm.

In another example, the preset transmission power values or thetransmission power values set by the base station, of the PSCCH, thePSSCH, and the PSFCH may be expressed as the transmission power valueand the offset value with respect to one channel. For example, when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH arepreset, the transmission power value of the PSCCH may be set to be [X]dBm, and the offset value for transmission power of the PSSCH and thePSFCH may be set to be +/−[Y] dB (or dBm), based on the transmissionpower value of the PSCCH. It may equally applied even when thetransmission power values of the PSCCH, the PSSCH, and the PSFCH are setby the base station.

FIG. 14 illustrates an operational flowchart of a V2X UE for sidelinktransmission power control according to an embodiment of the disclosure.

Referring to FIG. 14, the V2X transmission UE may determine whether theV2X transmission UE exists within the coverage of the base station (FIG.1A) or whether the V2X transmission UE exists out of the coverage of thebase station (FIG. 1C). Upon determining whether the V2X transmission UEexists within the coverage of the base station, the UE may obtaininformation on a sidelink resource pool at operation 1401. For example,upon recognizing that the UE exists within the coverage of the basestation, the UE may obtain information on a sidelink resource poolthrough RRC configuration or system information transmitted by the basestation. Unlike this, upon recognizing that the UE exists out of thecoverage of the base station, the UE may obtain information on asidelink resource pool through system information preconfigured in theUE.

Upon obtaining information on a resource pool from the base station orobtaining information on a preconfigured resource pool, the UE mayobtain information on sidelink transmission power parameters included insidelink resource pool information at operation 1402. The sidelinktransmission power parameters included in the sidelink resource poolinformation may include at least one of the following parameters.

P₀: A parameter for guaranteeing link quality of a reception UE

α: α is a parameter for guaranteeing a path loss value and has a valuebetween 0 and 1.

-   -   Number of RBs: A parameter on the size of frequency blocks that        the UE may use for transmitting sidelink control information and        data information    -   Subcarrier spacing: A parameter on a subcarrier spacing used for        transmitting sidelink control information and data information    -   A reference signal used for path loss estimation. That is, a        reference signal may indicate a synchronization signal        transmitted through downlink of the base station or a DMRS of a        physical broadcast channel (PBCH), which is transmitted through        downlink of the base station, or may indicate a parameter        indicating which signal the UE uses to estimate path loss, among        sidelink reference signals transmitted through sidelink between        UEs.    -   A parameter on multiplexing methods of a sidelink control        channel and a sidelink data channel (for example, information on        whether a channel is time-divided and transmitted as shown in        FIGS. 8, 9, and 12 or whether a channel is frequency-divided and        transmitted as shown in FIGS. 10 and 11.

The V2X transmission UE uses information on the parameters to settransmission powers of the sidelink control channel and the sidelinkdata channel at operation 1403. The V2X transmission UE uses the settransmission power value to transmit the sidelink control channel andthe sidelink data channel at operation 1404.

FIG. 15 is a diagram illustrating a UE configuration according to anembodiment of the disclosure.

Referring to FIG. 15, the UE according to an embodiment may include atransceiver 1520 and a controller 1510 configured to control the entireoperation of the UE. The transceiver 1520 may include a transmitter 1521and a receiver 1523.

The transceiver 1520 may transmit/receive a signal to/from other networkentities.

The controller 1510 may control the UE to perform one action of theembodiments mentioned above. Meanwhile, the controller 1510 and thetransceiver 1520 are not necessarily implemented as separate modules,and may be implemented as a single element in the form of a single chip.In addition, the controller 1510 and the transceiver 1520 may beelectrically connected to each other. For example, the controller 1510may be a circuit, an application-specific circuit, or at least oneprocessor. In addition, operations of the UE may be realized byproviding a memory device storing corresponding program codes to anyelement in the UE.

FIG. 16 is a diagram illustrating a base station's configurationaccording to an embodiment of the disclosure.

Referring to FIG. 16, the base station according to an embodiment mayinclude a transceiver 1620 and a controller 1610 configured to controlthe entire operation of the base station. The transceiver 1620 mayinclude a transmitter 1621 and a receiver 1623.

The transceiver 1620 may transmit/receive a signal to/from other networkentities.

The controller 1610 may control the base station to perform one actionof the embodiments mentioned above. Meanwhile, the controller 1610 andthe transceiver 1620 are not necessarily implemented as separatemodules, and may be implemented as a single element in the form of asingle chip. In addition, the controller 1610 and the transceiver 1620may be electrically connected to each other. For example, the controller1610 may be a circuit, an application-specific circuit, or at least oneprocessor. In addition, operations of the base station may be realizedby providing a memory device storing corresponding program codes to anyelement in the base station.

It should be noted that a configuration diagram, an exemplar diagram ofa control/data signal transmission method, an operational procedureexemplar diagram, and configuration diagrams, which are illustrated inFIGS. 1A to 1D, 2A and 2B, 3 to 16, are not intended to limit the scopeof the disclosure. That is, all of the elements, entities, or operationsdescribed in FIGS. 1A to 1D, 2A and 2B, 3 to 16 should not beinterpreted as essential elements for the implementation of thedisclosure, and only some of the elements can be used to implement thedisclosure within the scope which does not impair the nature of thedisclosure.

The above described operations of the base station or UE may beimplemented by providing a memory device storing corresponding programcodes to any element in the base station or UE. That is, the controllerof the base station or UE may perform the above described operations byreading and executing the program code stored in the memory device bymeans of a processor or a central processing unit (CPU). Methodsaccording to embodiments of the disclosure as defined by the appendedclaims or disclosed herein may be implemented in hardware, software, ora combination of hardware and software.

When the methods are implemented by software, a computer-readablestorage medium for storing one or more programs (software modules) maybe provided. The one or more programs stored in the computer-readablestorage medium may be configured for execution by one or more processorswithin the electronic device. The at least one program may includeinstructions that cause the electronic device to perform the methodsaccording to various embodiments of the disclosure as defined by theappended claims or disclosed herein.

The programs (software modules or software) may be stored innon-volatile memories including a random access memory and a flashmemory, a read only memory (ROM), an electrically erasable programmableread only memory (EEPROM), a magnetic disc storage device, a compactdisc-ROM (CD-ROM), digital versatile discs (DVDs), or other type opticalstorage devices, or a magnetic cassette. Alternatively, any combinationof some or all of them may form a memory in which the program is stored.Further, a plurality of such memories may be included in the electronicdevice.

In addition, the programs may be stored in an attachable storage devicewhich may access the electronic device through communication networkssuch as the Internet, Intranet, local area network (LAN), wide LAN(WLAN), and storage area network (SAN) or a combination thereof. Such astorage device may access an electronic device which performsembodiments of the disclosure, via an external port. Further, a separatestorage device on the communication network may access an electronicdevice which performs embodiments of the disclosure.

In the above-described detailed embodiments of the disclosure, anelement included in the disclosure is expressed in the singular or theplural according to a presented detailed embodiment. However, thesingular or plural expressions are selected to be suitable for proposedsituations for convenience of description, and the disclosure is notlimited to the singular or plural elements. An element expressed in aplural form may be configured in singular, or an element expressed in asingular form may be configured in plural.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a first user equipment (UE)in a wireless communication system, the method comprising: receiving,from a base station, a radio resource control (RRC) message includinginformation related to sidelink transmission power; determining sidelinktransmission power, based on the information; and transmitting asidelink control channel and a sidelink data channel, based on thedetermined sidelink transmission power, wherein the information includesat least one of downlink path loss-related information or sidelink pathloss-related information.
 2. The method of claim 1, wherein thedetermining of the sidelink transmission power comprises determining thesidelink transmission power, based on a minimum value between a firstsidelink transmission power calculated based on the downlink pathloss-related information and a second sidelink transmission powercalculated based on the sidelink path loss-related information in casethat the information includes both the downlink path loss-relatedinformation and the sidelink path loss-related information.
 3. Themethod of claim 1, further comprising: transmitting a sidelink referencesignal to a second UE; and receiving, from the second UE, referencesignals received power (RSRP) information which is measured based on thesidelink reference signal.
 4. The method of claim 1, wherein thesidelink transmission power is determined based onP _(PSSCH)(i)=min(P _(CMAX) ,P _(MAX,CBR),min(P _(PSSCH,D)(i),P_(PSSCH,SL)(i)))[dBm].
 5. The method of claim 4, wherein P_(MAX,CBR) isset to be 0 in case that there is no setting related to the P_(MAX,CBR)from the base station.
 6. A method performed by a base station in awireless communication system, the method comprising: transmitting, to afirst user equipment (UE), a radio resource control (RRC) messageincluding information related to sidelink transmission power; andreceiving, from the first UE, a sidelink control channel and a sidelinkdata channel, based on sidelink transmission power, wherein the sidelinktransmission power is determined based on the information, and whereinthe information includes at least one of downlink path loss-relatedinformation or sidelink path loss-related information.
 7. The method ofclaim 6, wherein, the sidelink transmission power is determined based ona minimum value between a first sidelink transmission power calculatedbased on the downlink path loss-related information and a secondsidelink transmission power calculated based on the sidelink pathloss-related information in case that the information includes both thedownlink path loss-related information and the sidelink pathloss-related information.
 8. The method of claim 6, wherein the first UEtransmits a sidelink reference signal to a second UE, and receivesreference signals received power (RSRP) information which is measuredbased on the sidelink reference signal.
 9. The method of claim 6,wherein the sidelink transmission power is determined based onP _(PSSCH)(i)=min(P _(CMAX) ,P _(MAX,CBR),min(P _(PSSCH,D)(i),P_(PSSCH,SL)(i)))[dBm].
 10. The method of claim 9, wherein P_(MAX,CBR) isset to be 0 in case that there is no setting related to the P_(MAX,CBR)from the base station.
 11. A first user equipment (UE) comprising: atransceiver configured to transmit or receive at least one signal; andat least one processor coupled to the transceiver, wherein the at leastone processor is configured to: receive, from a base station, a radioresource control (RRC) message including information related to sidelinktransmission power, determine sidelink transmission power, based on theinformation, and transmit a sidelink control channel and a sidelink datachannel, based on the determined sidelink transmission power, andwherein the information includes at least one of downlink pathloss-related information or sidelink path loss-related information. 12.The first UE of claim 11, wherein the at least one processor is furtherconfigured to, determine the sidelink transmission power, based on aminimum value between a first sidelink transmission power calculatedbased on the downlink path loss-related information and a secondsidelink transmission power calculated based on the sidelink pathloss-related information in case that the information includes both thedownlink path loss-related information and the sidelink pathloss-related information.
 13. The first UE of claim 11, wherein the atleast one processor is further configured to: transmit a sidelinkreference signal to a second UE, and receive, from the second UE,reference signals received power (RSRP) information which is measuredbased on the sidelink reference signal.
 14. The first UE of claim 11,wherein the sidelink transmission power is determined based onP _(PSSCH)(i)=min(P _(CMAX) ,P _(MAX,CBR),min(P _(PSSCH,D)(i),P_(PSSCH,SL)(i)))[dBm].
 15. The first UE of claim 14, wherein P_(MAX,CBR)is set to be 0 in case that there is no setting related to theP_(MAX,CBR) from the base station.
 16. A base station comprising: atransceiver configured to transmit or receive at least one signal; andat least one processor coupled to the transceiver, wherein the at leastone processor is configured to: transmit, to a first user equipment(UE), a radio resource control (RRC) message including informationrelated to sidelink transmission power, and receive, from the first UE,a sidelink control channel and a sidelink data channel, based onsidelink transmission power, wherein the sidelink transmission power isdetermined based on the information, and wherein the informationincludes at least one of downlink path loss-related information orsidelink path loss-related information.
 17. The base station of claim16, wherein, the sidelink transmission power is determined based on aminimum value between a first sidelink transmission power calculatedbased on the downlink path loss-related information and a secondsidelink transmission power calculated based on the sidelink pathloss-related information in case that the information includes both thedownlink path loss-related information and the sidelink pathloss-related information.
 18. The base station of claim 16, wherein thefirst UE transmits a sidelink reference signal to a second UE, andreceives reference signals received power (RSRP) information which ismeasured based on the sidelink reference signal.
 19. The base station ofclaim 16, wherein the sidelink transmission power is determined based onP _(PSSCH)(i)=min(P _(CMAX) ,P _(MAX,CBR),min(P _(PSSCH,D)(i),P_(PSSCH,SL)(i)))[dBm].
 20. The base station of claim 19, whereinP_(MAX,CBR) is set to be 0, in case that there is no setting related tothe P_(MAX,CBR) from the base station.